gcc.dg/no_profile_instrument_function-attr-1.c: Adjust for NO_DOT_IN_LABEL

gcc.dg/no_profile_instrument_function-attr-1.c: Adjust for NO_DOT_IN_LABEL

mmix-knuth-mmixware is a NO_DOT_IN_LABEL target, so it gets a "_"
instead of the "." in the identifier of interest.  Also tested and
compared to the output for cris-elf which is "regular" regarding
labels: there are no "false positive" identifiers there.  The "." in a
TCL bracket expression matches only a literal ".".

Committed as obvious.

gcc/testsuite:
	* gcc.dg/no_profile_instrument_function-attr-1.c: Adjust scanned
	regex for NO_DOT_IN_LABEL.