COFF has a 2**16 section limit, and on Win64, every COMDAT function creates at least 3 sections: .text, .pdata, and .xdata. For MSVC, we enable bigobj on a file-by-file basis, but GCC appears to hit the limit on different files. Fixes PR25953 llvm-svn: 290358
See docs/CMake.html for instructions on how to build LLVM with CMake.