[lld][WebAssembly] Fix spurious signature mismatch warnings
Summary:
This a follow up on: https://reviews.llvm.org/D62153
Handle the case where there are multiple object files that contain
undefined references to the same function. We only generate a function
variant if the existing symbol is directly called.
See: https://github.com/emscripten-core/emscripten/issues/8995
Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67015
llvm-svn: 370509