Summary:
Another smaller diff was responsible for breaking the build... D14019510 would have been the fix, which is integrated into this diff anyway.
---
Renaming FBMacros.h to FBDefines.h for more standard naming (similar to say UIKit/UIKit.h or Foundation/Foundation.h).
```
Tools/fastmod/fastmod --accept-all '\bFBMacros.h' FBDefines.h ../xplat
```
drop-conflicts
bypass-lint
allow-large-files
Reviewed By: dinhviethoa
Differential Revision: D14019529
fbshipit-source-id: 940490a5ec72ccdeb819598f488dc22eae454a26
3c35d6d4cf