Resolve pr44194-1.c failure by refining scan-rtl-dump-not pattern

[Eric Botcazou]

> This patch will resolve testsuite/gcc.dg/pr44194-1.c failure observed in
> aarch64 target by refining the second scan-rtl-dump-not pattern.
> 
> For aarch64 target, the following barrier is generated which will
> exactly match the current pattern
> "insn \[^\n\]*set \\(mem". This is undesired. By adjusting the pattern,
> this scenario is excluded.
> 
> (insn 29 28 30 (set (mem:BLK (scratch) [0  A8])
>          (unspec:BLK [
>                  (reg/f:DI 31 sp)
>                  (reg/f:DI 29 x29)
>              ] UNSPEC_PRLG_STK)) pr44194-1.c:10 704 {stack_tie}
>       (nil))

Please use "scratch" instead of "stack_tie" as marker, it's more general.

-- 
Eric Botcazou