corrected dubious use of the same variable twice in a function call,

gcc 3.0 warned about it

lib/mprintf.c

@@ -446,7 +446,7 @@ static int dprintf_Pass1(char *format, va_stack_t *vto, char **endpos, va_list a
 	case '1': case '2': case '3': case '4':
 	case '5': case '6': case '7': case '8': case '9':
 	  flags |= FLAGS_WIDTH;
-	  width = strtol(--fmt, &fmt, 10);
+	  width = strtol(fmt-1, &fmt, 10);
 	  break;
 	case '*':  /* Special case */
 	  flags |= FLAGS_WIDTHPARAM;