Rewrite StackMap location handling to pre-compute the dwarf register

numbers before emission.

This removes a dependency on being able to access TRI at the module
level and is similar to the DwarfExpression handling. I've modified
the debug support into print/dump routines that'll do the same dumping
but is now callable anywhere and if TRI isn't available will go ahead
and just print out raw register numbers.

llvm-svn: 232821