tools/selftests: add mq_perf_tests

Add the mq_perf_tests tool I used when creating my mq performance patch.
Also add a local .gitignore to keep the binaries from showing up in git
status output.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Doug Ledford <dledford@redhat.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/mqueue/.gitignore

+mq_open_tests
+mq_perf_tests

tools/testing/selftests/mqueue/Makefile

 all:
 	gcc -O2 -lrt mq_open_tests.c -o mq_open_tests
+	gcc -O2 -lrt -lpthread -lpopt -o mq_perf_tests mq_perf_tests.c
 
 run_tests:
 	./mq_open_tests /test1
+	./mq_perf_tests
 
 clean:
-	rm -f mq_open_tests
+	rm -f mq_open_tests mq_perf_tests