linux-user: Treat --foo options the same as -foo

The system mode binaries provide a similar alias
and it makes common options like --version and --help
work as expected.

Signed-off-by: Meador Inge <meadori@codesourcery.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

linux-user/main.c

@@ -4024,6 +4024,10 @@ static int parse_args(int argc, char **argv)
         if (!strcmp(r, "-")) {
             break;
         }
+        /* Treat --foo the same as -foo.  */
+        if (r[0] == '-') {
+            r++;
+        }
 
         for (arginfo = arg_table; arginfo->handle_opt != NULL; arginfo++) {
             if (!strcmp(r, arginfo->argv)) {