[binutils-gdb] format_pieces-selftests.c: Silence ARI warnings

[sergiodj+buildbot@sergiodj.net]

*** TEST RESULTS FOR COMMIT 1d143c36eedc0f0b124e6aa6fb3b98b1e6ff74b0 ***

Author: Simon Marchi <simon.marchi@ericsson.com>
Branch: master
Commit: 1d143c36eedc0f0b124e6aa6fb3b98b1e6ff74b0

format_pieces-selftests.c: Silence ARI warnings

Silence this:

unittests/format_pieces-selftests.c:51: warning: code: Do not use printf("%ll"), instead use printf("%s",phex()) to dump a `long long' value
unittests/format_pieces-selftests.c:56: warning: code: Do not use printf("%ll"), instead use printf("%s",phex()) to dump a `long long' value

gdb/ChangeLog:

	* unittests/format_pieces-selftests.c (test_format_specifier):
	Add ARI comments.