* rt/tst-timer4.c (TEST_CLOCK, TEST_CLOCK_NANOSLEEP): New macros.
Use them throughout in place of CLOCK_REALTIME and nanosleep.
(do_test) [TEST_CLOCK_MISSING]: Call this macro and if it returns
non-null, punt the test with a message using the string returned.
* rt/tst-timer5.c: New file.
* rt/Makefile (tests): Add it.