Both point to the same path for cc and cxx, but not for gcc_dir, which
makes no sense. That's the only significant difference between both, so
just merge them both, and use the merged file in the taskcluster build
script.
Instead, copy libgcc from the GCC used to build clang at each stage.
When passing --gcc-toolchain, the flag ends up appearing in the output
of llvm-config, and completely defeats the purpose of copying libgcc in
clang/lib/gcc.
Since build-clang.py requires a gcc_dir to be set, and we're using GCC
from there to build clang, we might as well copy libgcc from there
instead of building a fresh GCC. On the taskcluster job building clang,
GCC comes from a tooltool package that is already the result of
build-gcc anyways.
When passing -DCMAKE_C_COMPILER="gcc -flags" to CMake, ninja then tries
to literally call "gcc -flags", not "gcc" "-flags", and a "gcc -flags"
file obviously doesn't exist, so the build fails.
This fixes a regression from bug 1042132. Hopefully, this also doesn't
regress bug 1042132 itself.
Mike Hommey
Ehsan Akhgari