[WebAssembly] Add codegen support for the import_field attribute

This adds the LLVM side of https://reviews.llvm.org/D57602 -- the
import_field attribute. See that patch for details.

Differential Revision: https://reviews.llvm.org/D57603

llvm-svn: 352931
diff --git a/llvm/lib/MC/MCWasmStreamer.cpp b/llvm/lib/MC/MCWasmStreamer.cpp
index 8c47d68..6695a52 100644
--- a/llvm/lib/MC/MCWasmStreamer.cpp
+++ b/llvm/lib/MC/MCWasmStreamer.cpp
@@ -118,6 +118,7 @@
     break;
 
   case MCSA_ELF_TypeObject:
+  case MCSA_Cold:
     break;
 
   default: