C++ atomic's fetch_sub returns the previous value, where we want to
check the new value. This was causing massive memory leaks in SourceKit.
For ThreadSafeRefCountedBase, just switch to the one in LLVM that's
already correct. We should move the VPTR one to LLVM as well and then
we can get rid of this header.
rdar://problem/27358273
- Added missing ifdef guard in PointerIntEnum header
- Consistent naming convention for ifdef guards
- Consistent 'end namespace swift'
- Consistent single EOL at end of header files
