Add support for FreeBSD on PowerPC64

[lenoil98]

The changes add support for building rustc on freebsd powerpc64. Reference issue #57112

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @pnkfelix (or someone else) soon.

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[nagisa]

r? @nagisa

[rust-highfive]

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:end:09602bcb:start=1547914667750290587,finish=1547914737519412162,duration=69769121575
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
Setting environment variables from .travis.yml
$ export IMAGE=x86_64-gnu-llvm-6.0
---
[00:23:40] 20  | fn main() {
[00:23:40]     |           - un-closed delimiter
[00:23:40] ...
[00:23:40] 269 |             } else {
[00:23:40]     |                    - this delimiter might not be properly closed...
[00:23:40] 270 |                 println!("cargo:rustc-link-lib={}", stdcppname);
[00:23:40] 271 |         }
[00:23:40]     |         - ...as it matches this but it has different indentation
[00:23:40] 281 | }
[00:23:40]     |   ^
[00:23:40] 
[00:23:40] error: aborting due to previous error
---
[00:23:40] travis_fold:start:stage0-rustc_codegen_llvm
travis_time:start:stage0-rustc_codegen_llvm
failed to run: /checkout/obj/build/bootstrap/debug/bootstrap build
[00:23:40] Build completed unsuccessfully in 0:20:26
[00:23:40] Makefile:18: recipe for target 'all' failed
[00:23:40] make: *** [all] Error 1
74508 ./.git/modules/src
73896 ./src/llvm/lib
69912 ./src/llvm-emscripten/lib
69124 ./src/test
---
travis_time:end:279e286c:start=1547916167888057307,finish=1547916167892783822,duration=4726515
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:049bd752
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:0aac56b1
travis_time:start:0aac56b1
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:0948518a
$ dmesg | grep -i kill

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[bors]

☔ The latest upstream changes (presumably #57704) made this pull request unmergeable. Please resolve the merge conflicts.

[nagisa]

This particular piece of code should perhaps be moved slightly up to where stdcppname variable is assigned.

[nagisa]

Does llvm-config not print this path out? If I remember my freebsd correctly, this would mean that gcc would be required to build rustc then. Which is not that big of a deal, but still something to improve on.

[ghost]

FreeBSD on powerpc64 ships an old version of gcc (4.2.1) in the 'base' system, since it can't build llvm I had to use gcc7 from our 'ports tree'. For whatever reason the linker tried to link 'something' against libstdc++ from gcc-4.2.1 instead of libstdc++ from gcc7 and the link failed (I was not able to figure out how to pass -Wl,-rpath=/usr/local/lib/gcc7). Linking to a static version of libstdc++ made the problem go away.
This is just an ugly hack to fix a FreeBSD problem and should probably stays as a patch file in our 'ports tree'

[nagisa]

The changes look good. Please squash the commits together into one or two and give these commits a description that makes it obvious what these changes are about (i.e. "Add support for powerpc64-unknown-freebsd target" instead of "Update file.rs"). You should also remove the merge commit as a part of the rebase process.

You can read about rebasing here (also here) and here about rewriting the commit (and its message).

[nagisa]

Closing in favour of #57809. Thanks!

[ghost]

Can you put gcc8, this is our default gcc version since a few weeks.