Fix arm/arm64 localloc

Fix arm/arm64 localloc

In the loop, non-initialized memory case, the stack probing code
had silent bad codegen, as follows:
```
mov     r4, 0x4000
subs    r4, sp, r4
bvc     SHORT G_M3294_IG03
movs    r4, 0

G_M3294_IG03:

ldr     r0, [sp]
sub     r0, sp, 0x1000
cmp     r0, r4
blo     SHORT G_M3294_IG04
mov     sp, r0              // Before fix, this was "mov sp, r4"
b       SHORT G_M3294_IG03

G_M3294_IG04:
```