Several performance-oriented changes to the introspecting data formatters:

 (a) the SystemParameters object is now passed around to the formatters; doing so enables the formatters to reuse computed values for things such as pointer-size and endianness
     instead of repeatedly computing these on their own
 (b) replacing the global ISA cache with a per-process one
 (c) providing a per-process types cache where each formatter can store the types it needs to operate, and be sure to find them the next time without recalculating them
     this also enables formatters to share types if they agree on a local naming convention
 (d) lazy fetching of data from Objective-C runtime data structures
     data is fetched as needed and we stop reading as soon as we determine that an ISA is actually garbage

llvm-svn: 152052