[testsuite] Fix gcc.dg/pr115066.c fail on aarch64

[testsuite] Fix gcc.dg/pr115066.c fail on aarch64

On aarch64, I get this failure:
...
FAIL: gcc.dg/pr115066.c scan-assembler \\.byte\\t0xb\\t# Define macro strx
...

This happens because we expect to match:
...
        .byte   0xb     # Define macro strx
...
but instead we get:
...
        .byte   0xb     // Define macro strx
...

Fix this by not explicitly matching the comment marker.

Tested on aarch64 and x86_64.

gcc/testsuite/ChangeLog:

2024-05-14  Tom de Vries  <tdevries@suse.de>

	* gcc.dg/pr115066.c: Don't match comment marker.