lavf/url: fix relative url parsing when the query string or fragment has a colon

This disallows the usage of ? and # in libavformat specific scheme options
(e.g. subfile,,start,32815239,end,0,,:video.ts) but this change was considered
acceptable.

Signed-off-by: ruiquan.crq <caihaoning83@gmail.com>
Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/tests/url.c

@@ -90,6 +90,8 @@ int main(void)
     test_decompose("http://[::1]/dev/null");
     test_decompose("http://[::1]:8080/dev/null");
     test_decompose("//ffmpeg/dev/null");
+    test_decompose("test?url=http://server/path");
+    test_decompose("dummy.mp4#t=0:02:00,121.5");
 
     printf("Testing ff_make_absolute_url:\n");
     test(NULL, "baz");