tests: add rt_sigprocmask.test

* tests/rt_sigprocmask.c: New file.
* tests/rt_sigprocmask.test: New test.
* tests/.gitignore: Add rt_sigprocmask.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(TESTS): Add rt_sigprocmask.test.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index db23808..7030a29 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -130,6 +130,7 @@
 	recvmsg \
 	restart_syscall \
 	rt_sigpending \
+	rt_sigprocmask \
 	rt_sigqueueinfo \
 	sched_xetaffinity \
 	sched_xetattr \
@@ -281,6 +282,7 @@
 	readv.test \
 	recvmsg.test \
 	rt_sigpending.test \
+	rt_sigprocmask.test \
 	rt_sigqueueinfo.test \
 	sched_xetaffinity.test \
 	sched_xetattr.test \