Userland: Return 1 when help text is shown for insufficient args

ArgsParser also does this, but we don't use that (yet) in a couple of
places. Fix the behaviour manually for consistency.

Userland/Utilities/chown.cpp

@@ -22,7 +22,7 @@ int main(int argc, char** argv)
 
     if (argc < 3) {
         warnln("usage: chown <uid[:gid]> <path>");
-        return 0;
+        return 1;
     }
 
     uid_t new_uid = -1;

Userland/Utilities/fgrep.cpp

@@ -14,7 +14,7 @@ int main(int argc, char** argv)
 {
     if (argc < 2) {
         warnln("usage: fgrep <str>");
-        return 0;
+        return 1;
     }
     for (;;) {
         char buf[4096];

Userland/Utilities/flock.cpp

@@ -16,7 +16,7 @@ int main(int argc, char** argv)
 {
     if (argc < 3) {
         warnln("usage: flock <path> <command...>");
-        return 0;
+        return 1;
     }
 
     pid_t child_pid;

Userland/Utilities/gron.cpp

@@ -44,7 +44,7 @@ int main(int argc, char** argv)
     if (argc != 2 || !strcmp(argv[1], "--help")) {
         warnln("usage: gron <file>");
         warnln("Print each value in a JSON file with its fully expanded key.");
-        return 0;
+        return argc != 2 ? 1 : 0;
     }
     auto file = Core::File::construct(argv[1]);
     if (!file->open(Core::OpenMode::ReadOnly)) {

Userland/Utilities/mknod.cpp

@@ -18,7 +18,7 @@ constexpr unsigned encoded_device(unsigned major, unsigned minor)
 static int usage()
 {
     warnln("usage: mknod <name> <c|b|p> [<major> <minor>]");
-    return 0;
+    return 1;
 }
 
 int main(int argc, char** argv)