* Replaced uses in opcode validation of current_function()
* Added non-const accessor to function lookup in ValidationState_t
* Updated a couple bad tests due to check reordering
This CL splits the switch in ImagePass into individual validate
functions. The error messages have been updated to drop the
suffix/prefix of the opcode name since it will be displayed in the
disassembly.
This CL moves the various validate files into the val/ directory with
the rest of the validation infrastructure. This matches how opt/ is
setup with the passes with the infrastructure.