add addrmode2 support, getting us up to:

_main:
	stm , 
	mov r7, sp
	sub sp, sp, #4
	mov r0, #0
	str r0, [sp]
	ldr r0, LCPI1_0
	bl _printf
	ldr r0, [sp]
	mov sp, r7
	ldm , 

llvm-svn: 84543