selftests: vm: return Kselftest Skip code for skipped tests

When vm test is skipped because of unmet dependencies and/or unsupported
configuration, it exits with error which is treated as a fail by the
Kselftest framework. This leads to false negative result even when the
test could not be run.

Change it to return kselftest skip code when a test gets skipped to
clearly report that the test could not be run.

Kselftest framework SKIP code is 4 and the framework prints appropriate
messages to indicate that the test is skipped.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/vm/compaction_test.c

@@ -16,6 +16,8 @@
 #include <unistd.h>
 #include <string.h>
 
+#include "../kselftest.h"
+
 #define MAP_SIZE 1048576
 
 struct map_list {
@@ -169,7 +171,7 @@ int main(int argc, char **argv)
 		printf("Either the sysctl compact_unevictable_allowed is not\n"
 		       "set to 1 or couldn't read the proc file.\n"
 		       "Skipping the test\n");
-		return 0;
+		return KSFT_SKIP;
 	}
 
 	lim.rlim_cur = RLIM_INFINITY;