* Fix ICG errors while processing system header files #1189
Found an InitPreprocessor call and am using it. Not sure which version
of clang it was added, just using for the version I'm on (10) and above.
Also found some GCC defines that are used during normal compilation.
Added these to our list of defines during ICG. This clears up all of
the errors I've been seeing.
* Fix ICG errors while processing system header files #1189
OK, found the flag that activates the ATOMIC defines I was previously
hardcoding.