[Windows] Adjust exported symbols to filter out profile symbols (#167985)
When building Clang for Windows with clang-cl with -fprofile-generate
and LLVM_EXPORT_SYMBOLS_FOR_PLUGINS, the build fails with
lld-link: error: too many exported symbols (got 76137, max 65535)
Removing the symbols generated from the use of that flag removes about
13K symbols.