[PATCH] Add try_to_freeze() to rt-test kthreads

When CONFIG_RT_MUTEX_TESTER is enabled kernel refuses to suspend the
machine because it's unable to freeze the rt-test-* threads.

Add try_to_freeze() after schedule() so that the threads will be freezed
correctly; I've tested the patch and it lets the notebook suspends and
resumes nicely.

Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>