Match against multi instruction patterns in arm.md

[DontBelieveMe]

e.g.

(define-insn "load_sgptr"
	[(kInsn_Load
		(match_operand:ptr 0 "global")
		(match_operand:i32 1 "register"))
         (kInsn_SignExtend
		(match_operand:i8 0 "register")
		(match_operand:i32 1 "register"))]
	"movw {1}, :lower16:{0}"
	"movt {1}, :upper16:{0}"
	"ldrsb {1}, [{1}]")

Required for #10 - so that the correct load instruction (e.g. ldrsb, ldrb, ldrsh, ldrh etc...) can be generated when loading from globals that are smaller than 32 bits in size)

[DontBelieveMe]

Moving down from critical -> medium now that it is possible to write code to account for these situations