[WebAssembly] Basic support for Wasm object file encoding.

With the "wasm32-unknown-unknown-wasm" triple, this allows writing out
simple wasm object files, and is another step in a larger series toward
migrating from ELF to general wasm object support. Note that this code
and the binary format itself is still experimental.

llvm-svn: 296190
diff --git a/llvm/test/CodeGen/WebAssembly/implicit-def.ll b/llvm/test/CodeGen/WebAssembly/implicit-def.ll
index 01ee171..1f9f748 100644
--- a/llvm/test/CodeGen/WebAssembly/implicit-def.ll
+++ b/llvm/test/CodeGen/WebAssembly/implicit-def.ll
@@ -1,6 +1,6 @@
 ; RUN: llc -o - %s | FileCheck %s
 target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
-target triple = "wasm32-unknown-unknown"
+target triple = "wasm32-unknown-unknown-wasm"
 
 ; Test that stackified IMPLICIT_DEF instructions are converted into
 ; CONST_I32 to provide an explicit push.