<rdar://problem/13210494>

Parse objective C information as efficiently as possible and without taking dangerous runtime locks.

Reworked the way objective C information is parsed by:
1 - don't read all class names up front, this is about 500K of data with names
2 - add a 32 bit hash map that maps a hash of a name to the Class pointer (isa)
3 - Improved name lookups by using the new hash map
4 - split up reading the objc runtime info into dynamic and shared cache since the shared cache only needs to be read once.
5 - When reading all isa values, also get the 32 bit hash instead of the name
6 - Read names lazily now that we don't need all names up front
7 - Allow the hash maps to not be there and still have this function correctly

There is dead code in here with all of the various methods I tried. I want to check this in first to not lose any of it in case we need to revert to any of the extra code. I will promptly cleanup and commit again.

llvm-svn: 175101