Use correct add*Imm form in more BuildMI calls.

Fix bug in emitGEPOperation where we weren't passing MBB, IP to getReg.
(hey, wouldn't a constant expression lowering pass be cool? huh huhuhuh)
Fix bug in emitGEPOperation where we might try to OR a constant into a
register which was too big to fit in the immediate field.
Support and, or, xor of longs.

llvm-svn: 14363