[WebAssembly] Explicily disable comdat support for wasm output

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

llvm-svn: 318123

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -1825,10 +1825,10 @@ Expected<Value *> BitcodeReader::recordValue(SmallVectorImpl<uint64_t> &Record,
   auto *GO = dyn_cast<GlobalObject>(V);
   if (GO) {
     if (GO->getComdat() == reinterpret_cast<Comdat *>(1)) {
-      if (TT.isOSBinFormatMachO())
-        GO->setComdat(nullptr);
-      else
+      if (TT.supportsCOMDAT())
         GO->setComdat(TheModule->getOrInsertComdat(V->getName()));
+      else
+        GO->setComdat(nullptr);
     }
   }
   return V;