This patch replaces signed integer types with signless ones:
1. [US]Byte -> Int8
2. [U]Short -> Int16
3. [U]Int   -> Int32
4. [U]Long  -> Int64.
5. Removal of isSigned, isUnsigned, getSignedVersion, getUnsignedVersion
   and other methods related to signedness. In a few places this warranted
   identifying the signedness information from other sources.

llvm-svn: 32785