Added the darwin .weak_def_can_be_hidden directive.

llvm-svn: 107886
diff --git a/llvm/lib/MC/MCMachOStreamer.cpp b/llvm/lib/MC/MCMachOStreamer.cpp
index 3febda0..44bc267 100644
--- a/llvm/lib/MC/MCMachOStreamer.cpp
+++ b/llvm/lib/MC/MCMachOStreamer.cpp
@@ -273,6 +273,10 @@
     // it has to be in a coalesced section, but this isn't enforced.
     SD.setFlags(SD.getFlags() | SF_WeakDefinition);
     break;
+
+  case MCSA_WeakDefAutoPrivate:
+    SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
+    break;
   }
 }