Driver: Ignore -fobjc-gc and -fobjc-gc-only for platforms which don't support them.

llvm-svn: 100930
diff --git a/clang/lib/Driver/ToolChains.h b/clang/lib/Driver/ToolChains.h
index 0d5b2a3..9e61b89 100644
--- a/clang/lib/Driver/ToolChains.h
+++ b/clang/lib/Driver/ToolChains.h
@@ -176,6 +176,8 @@
   virtual const char *GetDefaultRelocationModel() const;
   virtual const char *GetForcedPicModel() const;
 
+  virtual bool SupportsObjCGC() const;
+
   virtual bool UseDwarfDebugFlags() const;
 
   virtual bool UseSjLjExceptions() const;