For now at least. We clearly need some kind of comdat or
linkonce_odr support for wasm but currently COMDAT is not
supported.
Disable COMDAT support in the same way we do the Mach-O. This
also causes clang not to generated COMDATs.
Differential Revision: https://reviews.llvm.org/D39873
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318123 91177308-0d34-0410-b5e6-96231b3b80d8