add register list and hacked up addrmode #4 support, we now get this:

_main:
	stmsp! sp!, {r7, lr}
	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
	ldmsp! sp!, {r7, pc}

Note the unhappy ldm/stm because of modifiers being ignored.

llvm-svn: 84546