Add -g flag to generate debuginfo on unix platforms (dotnet/corefx#24979

)

The windows build already includes /Zi /Zl as part of commit 920fd2f
(PR dotnet/corefx#7840). It looks like it was simply missed on Unix.

This change also makes the native debug information closer to what
CoreCLR does on all platforms. See
dotnet/coreclr#3445 for more information.

This is also needed for the end-to-end debuginfo generation as part of
source-build. See dotnet/source-build#267

Commit migrated from dotnet/corefx@efe7652

src/libraries/Native/Unix/CMakeLists.txt

@@ -20,6 +20,7 @@ add_compile_options(-fPIC)
 add_compile_options(-I${CMAKE_CURRENT_SOURCE_DIR}/Common)
 add_compile_options(-I${CMAKE_CURRENT_BINARY_DIR}/Common)
 add_compile_options(-Wno-c99-extensions)
+add_compile_options(-g)
 
 if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.5)
     add_compile_options(-Wno-unreachable-code)
@@ -60,7 +61,7 @@ endif ()
 
 string(TOUPPER ${CMAKE_BUILD_TYPE} UPPERCASE_CMAKE_BUILD_TYPE)
 if (UPPERCASE_CMAKE_BUILD_TYPE STREQUAL DEBUG)
-    add_compile_options(-g -O0)
+    add_compile_options(-O0)
     add_definitions(-DDEBUG)
 
     # obtain settings from running coreclr\enablesanitizers.sh