Do not give a warning for -dD, -dI, or -dM

From-SVN: r24390

gcc/ChangeLog

@@ -1,3 +1,8 @@
+Mon Dec 21 17:39:38 1998  Michael Meissner  <meissner@cygnus.com>
+
+	* toplev.c (main): Don't emit any warnings when using -dD, -dM, or
+	-dI, which are handled by the preprocessor.
+
 Sun Dec 20 16:13:44 1998  John F. Carr  <jfc@mit.edu>
 
 	* configure.in: Handle Digital UNIX 5.x the same as 4.x.

gcc/toplev.c

@@ -4786,6 +4786,10 @@ main (argc, argv)
 		  case 'x':
 		    rtl_dump_and_exit = 1;
 		    break;
+		  case 'D':	/* these are handled by the preprocessor */
+		  case 'I':
+		  case 'M':
+		    break;
 		  default:
 		    warning ("unrecognised gcc debugging option: %c", p[-1]);
 		    break;