This adds the /DEBUG:GHASH option to LLD which will look for
the existence of .debug$H sections in linker inputs and use them
to accelerate type merging. The clang-cl side has already been
added, so this completes the work necessary to begin experimenting
with this feature.
Differential Revision: https://reviews.llvm.org/D40980
llvm-svn: 320719
Zachary Turner