Add missing noreturn attribute to various functions

Signed-off-by: Thomas Wood <thomas.wood@intel.com>

tests/gem_madvise.c

@@ -49,7 +49,7 @@ IGT_TEST_DESCRIPTION("Checks that the kernel reports EFAULT when trying to use"
 
 static jmp_buf jmp;
 
-static void sigtrap(int sig)
+static void __attribute__((noreturn)) sigtrap(int sig)
 {
 	longjmp(jmp, sig);
 }

tests/pm_rpm.c

@@ -1386,7 +1386,7 @@ static void pci_d3_state_subtest(void)
 	igt_assert(!device_in_pci_d3());
 }
 
-static void stay_subtest(void)
+static void __attribute__((noreturn)) stay_subtest(void)
 {
 	disable_all_screens_and_wait(&ms_data);
 

tests/testdisplay.c

@@ -552,7 +552,7 @@ static void __attribute__((noreturn)) usage(char *name, char opt)
 
 #define dump_resource(res) if (res) dump_##res()
 
-static void cleanup_and_exit(int ret)
+static void __attribute__((noreturn)) cleanup_and_exit(int ret)
 {
 	close(drm_fd);
 	exit(ret);