testsuite: btf: fix regexps in btf-int-1.c

The regexps in hte test btf-int-1.c were not working properly with the
commenting style of at least one target: powerpc64le-linux-gnu.  This
patch changes the test to use better regexps.

Tested in bpf-unkonwn-none, x86_64-linux-gnu and powerpc64le-linux-gnu.
Pushed to master as obvious.

gcc/testsuite/ChangeLog:

	PR testsuite/106515
	* gcc.dg/debug/btf/btf-int-1.c: Fix regexps in
	scan-assembler-times.