[WebAssembly] Remove unused function return types (NFC)

Reviewers: sbc100

Subscribers: dschuff, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54734

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347277 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed