qemu-option: fix parse_option_number().

It works much better when parse_option_number actually
returns the number parsed ...

Common breakage resulting from this bug is that
'qemu -hda foo.img -cdrom bar.iso' stops working
(cdrom isn't there).

Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

qemu-option.c

@@ -193,6 +193,7 @@ static int parse_option_number(const char *name, const char *value, uint64_t *re
             fprintf(stderr, "Option '%s' needs a number as parameter\n", name);
             return -1;
         }
+        *ret = number;
     } else {
         fprintf(stderr, "Option '%s' needs a parameter\n", name);
         return -1;