add -fPIC for cxx_cc so that it can link in clang properly

[sthornington]

Fixes linking in clang toolchains, e.g. #1399

[dtolnay]

This looks odd to me. -fPIC is something that needs to be seen by every C++ compiler invocation in a whole build. It isn't something that individual cc_library targets should be deciding to pass or not pass. Do you have more context about why this is the right fix?

[sthornington]

This looks odd to me. -fPIC is something that needs to be seen by every C++ compiler invocation in a whole build. It isn't something that individual cc_library targets should be deciding to pass or not pass. Do you have more context about why this is the right fix?

Ultimately, I was just following clang's suggestion during trying to get it all working with clang in #1399

/usr/bin/ld.gold: error: bazel-out/k8-dbg/bin/external/crate_index__cxx-1.0.130/libcxx_cc.a(cxx.o): requires dynamic R_X86_64_32 reloc against '__gxx_personality_v0' which may overflow at runtime; recompile with -fPIC

[sthornington]

I have great stake in how this is done, but this is the only thing that fixed it for me when building with a clang cc toolchain - have you been able to build it all in Linux with clang some other way?

[sthornington]

Sorry I meant "I have no great stake in how it all gets done", I just need to be able to link rust and C++ and cxx bindings in both gcc and clang in bazel.

[sthornington]

Ok I just added it to my bazelrc and that does the same trick. I guess I don't need this merged after all, but it's here if you want it.

[sthornington]

That said, I have other issues... when compiling with -fsanitize stuff, it complains that that particular archive is missing __UBSAN symbols etc.