Add a getName accessor for ModuleMacros.

Swift would like to be able to access the name of a ModuleMacro.
There was some discussion of this in
apple/swift-clang#93, suggesting that it makes
sense to have this accessor in Clang.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@310622 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Lex/MacroInfo.h

@@ -510,6 +510,9 @@ class ModuleMacro : public llvm::FoldingSetNode {
     ID.AddPointer(II);
   }
 
+  /// Get the name of the macro.
+  IdentifierInfo *getName() const { return II; }
+
   /// Get the ID of the module that exports this macro.
   Module *getOwningModule() const { return OwningModule; }