Support: adjust the default obj format for wasm

WebAssemly uses a custom object file format.  For the wasm targets,
default to the `Wasm` object file format.

llvm-svn: 304117

Author: compnerd

llvm/lib/Support/Triple.cpp

@@ -643,11 +643,13 @@ static Triple::ObjectFormatType getDefaultFormat(const Triple &T) {
   case Triple::tce:
   case Triple::tcele:
   case Triple::thumbeb:
-  case Triple::wasm32:
-  case Triple::wasm64:
   case Triple::xcore:
     return Triple::ELF;
 
+  case Triple::wasm32:
+  case Triple::wasm64:
+    return Triple::Wasm;
+
   case Triple::ppc:
   case Triple::ppc64:
     if (T.isOSDarwin())