support: Add missing EOL terminators on timespec

The original implementations of test_timespec_before_impl and
test_timespec_equal_or_after in 51983996
were missing the backslash required for a newline.

Checked on x86_64-linux-gnu.

	* support/timespec.c: Add backslash to correct newline in failure
	message.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>