Print macro name fix

[PappasBrent]

• Adds a new method to the MacroSubstitution class for getting the names of substituted macros.
• Uses this new method to correct the output of some of the binaries for printing covering macros.
• Silences a small warning in the PrintMacroGraph binary about an implicit cast from a string value to a Boolean value.

[PappasBrent]

I think you should modify PatchedMacroTracker.cpp to keep track of the actual name. For example, you would add a Node name; field...

Should I add this field to the MacroSubstitutionImpl class or MacroNodeImpl?

[pgoodman]

Should I add this field to the MacroSubstitutionImpl class or MacroNodeImpl?

The former.