Define WeakRefDirective.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132098 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsMCAsmInfo.cpp b/lib/Target/Mips/MipsMCAsmInfo.cpp
index fe48ab7..ca00463 100644
--- a/lib/Target/Mips/MipsMCAsmInfo.cpp
+++ b/lib/Target/Mips/MipsMCAsmInfo.cpp
@@ -24,4 +24,5 @@
   ZeroDirective               = "\t.space\t";
   GPRel32Directive            = "\t.gpword\t";
   HasSetDirective             = false;
+  WeakRefDirective            = "\t.weak\t";
 }