add libgit2

[jeroen]

Relatively small lib to support the gert package and perhaps others:

configure: sh -c "./configure.orig --build=x86_64-pc-linux-gnu --host=wasm32-unknown-emscripten"

Found pkg-config cflags and libs!
Using PKG_CFLAGS=-sUSE_ZLIB=1 -I/opt/webr/wasm/include
Using PKG_LIBS=-L/opt/webr/wasm/lib -lgit2 -lrt -sUSE_ZLIB=1
Configuration OK!
** libs
using C compiler: 'emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.47 (431685f05c67f0424c11473cc16798b9587bb536)'
rm -f gert.so branch.o clone.o commit.o config.o conflicts.o files.o ignore.o init.o merge.o rebase.o stash.o submodules.o tag.o utils.o version.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c branch.c -o branch.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c clone.c -o clone.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c commit.c -o commit.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c config.c -o config.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c conflicts.c -o conflicts.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c files.c -o files.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c ignore.c -o ignore.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c init.c -o init.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c merge.c -o merge.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c rebase.c -o rebase.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c stash.c -o stash.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c submodules.c -o submodules.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c tag.c -o tag.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c utils.c -o utils.o
emcc -DNDEBUG -sUSE_ZLIB=1 -I/opt/webr/wasm/include -DR_NO_REMAP -DSTRICT_R_HEADERS  -I/opt/webr/wasm/include -I/opt/webr/R/build/R-4.3.0/build/include -I/opt/webr/R/build/R-4.3.0/src/include -s USE_BZIP2=1 -s USE_ZLIB=1 -fvisibility=hidden -fpic  -Oz -fPIC -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -std=gnu11 -c version.c -o version.o
emcc -s SIDE_MODULE=1 -s WASM_BIGINT -s ASSERTIONS=1 -L/opt/webr/wasm/lib -L/opt/webr/wasm/R-4.3.0/lib/R/lib -s USE_BZIP2=1 -s USE_ZLIB=1 -fwasm-exceptions -s SUPPORT_LONGJMP=wasm -Oz -o gert.so branch.o clone.o commit.o config.o conflicts.o files.o ignore.o init.o merge.o rebase.o stash.o submodules.o tag.o utils.o version.o -L/opt/webr/wasm/lib -lgit2 -lrt -sUSE_ZLIB=1
installing to /tmp/RtmpyJiunL/file4075627f70bf/gert/libs
** R
** inst
** preparing package for lazy loading
** help
*** installing help indices
*** copying figures
** building package indices
** installing vignettes
* creating tarball
packaged installation of 'gert' as 'gert_2.0.1_R_x86_64-pc-linux-gnu.tar.gz'
* DONE (gert)
Packaging: gert_2.0.1.data

[jeroen]

Deployed this on R-universe and confirm that it works.

install.packages('gert', repos = sprintf('https://%s.r-universe.dev', c('ropensci', 'cran')))

library(gert)
writeLines("Test", "test.txt")
gert::git_init()
gert::git_add("test.txt")
gert::git_status()
git_config_set("user.name", "Jerry")
git_config_set("user.email", "[email protected]")
gert::git_commit("first commit")
gert::git_log()