pmap: restore a proper response when arguments missing

Ever since pmap was refactored via the reference below
(and sprinkled with those damn tabs), the response for
the absence of any argument has been an error message.

This patch restores the proper behavior ('usage' text)
and updates the dejagnu 'no arguments' expect pattern.

Reference(s):
commit d50884788d

Signed-off-by: Jim Warner <james.warner@comcast.net>

pmap.c

@@ -994,6 +994,9 @@ int main(int argc, char **argv)
 	textdomain(PACKAGE);
 	atexit(close_stdout);
 
+	if (argc < 2)
+		usage(stderr);
+
 	while ((c = getopt_long(argc, argv, "xXrdqA:hVcC:nN:p", longopts, NULL)) != -1)
 		switch (c) {
 		case 'x':