Add a getName accessor for ModuleMacros

[bob.wilson]

Summary

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

[bob.wilson]

Committed in r310622

clang/Lex/MacroInfo.h

void Profile(llvm::FoldingSetNodeID &ID) const {
     return Profile(ID, OwningModule, II);
   }
   static void Profile(llvm::FoldingSetNodeID &ID, Module *OwningModule,
                       IdentifierInfo *II) {
     ID.AddPointer(OwningModule);
     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; }
 
   /// Get definition for this exported #define, or nullptr if this
   /// represents a #undef.
   MacroInfo *getMacroInfo() const { return Macro; }
 
   /// Iterators over the overridden module IDs.