sigreturn.test: use RT_5 signal number instead of RT_2

Make the test compatible with musl libc that uses RT_2 internally.

* tests/sigreturn.c (main): Replace RT_2 with RT_5.
* tests/sigreturn.test: Likewise.

Reported-by: Szabolcs Nagy <nsz@port70.net>
diff --git a/tests/sigreturn.c b/tests/sigreturn.c
index f6284c8..dace040 100644
--- a/tests/sigreturn.c
+++ b/tests/sigreturn.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 Dmitry V. Levin <ldv@altlinux.org>
+ * Copyright (c) 2015-2016 Dmitry V. Levin <ldv@altlinux.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -45,9 +45,9 @@
 	sigemptyset(&set);
 	sigaddset(&set, SIGUSR2);
 	sigaddset(&set, SIGCHLD);
-	sigaddset(&set, RT_0 +  2);
 	sigaddset(&set, RT_0 +  3);
 	sigaddset(&set, RT_0 +  4);
+	sigaddset(&set, RT_0 +  5);
 	sigaddset(&set, RT_0 + 26);
 	sigaddset(&set, RT_0 + 27);
 	sigprocmask(SIG_SETMASK, &set, NULL);
diff --git a/tests/sigreturn.test b/tests/sigreturn.test
index bc8dcbd..f9a612b 100755
--- a/tests/sigreturn.test
+++ b/tests/sigreturn.test
@@ -2,7 +2,7 @@
 #
 # Check rt_sigprocmask and sigreturn/rt_sigreturn decoding.
 #
-# Copyright (c) 2015 Dmitry V. Levin <ldv@altlinux.org>
+# Copyright (c) 2015-2016 Dmitry V. Levin <ldv@altlinux.org>
 # All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
@@ -32,7 +32,7 @@
 run_prog
 run_strace -esignal $args
 
-mask='\[(USR2 CHLD|CHLD USR2) RT_2 RT_3 RT_4 RT_26 RT_27\]'
+mask='\[(USR2 CHLD|CHLD USR2) RT_3 RT_4 RT_5 RT_26 RT_27\]'
 rt_sigprocmask='rt_sigprocmask\(SIG_SETMASK, '"$mask"', NULL, [[:digit:]]+\) += 0'
 osf_sigprocmask='osf_sigprocmask\(SIG_SETMASK, '"$mask"'\) += 0 +\(old mask \[[^]]*\]\)'
 EXPECTED="$LOG.expected"