<rdar://problem/12331741>

Dynamic type code must be efficient and fast. Now it is.

Added ObjC v1 support for getting the complete list of ISA values.

The main flow of the AppleObjCRuntime subclasses is now they must override "virtual bool UpdateISAToDescriptorMap_Impl();". This function will update the complete list of ISA values and create ClassDescriptorSP objects for each one. Now we have the complete list of valid ISA values which we can use for verification when doing dynamic typing.

Refactored a bunch of stuff so that the AppleObjCRuntime subclasses don't have to implement as many functions as they used to.

llvm-svn: 165730