url: patched to compile on Android.

src/misc/SDL_url.c

@@ -18,7 +18,6 @@
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
-
 #include "../SDL_internal.h"
 #include "SDL_error.h"
 

src/misc/android/SDL_sysurl.c

@@ -25,6 +25,7 @@
 int
 SDL_SYS_OpenURL(const char *url)
 {
+    jclass mActivityClass = Android_GetActivityClass();
     JNIEnv *env = Android_JNI_GetEnv();
     jstring jurl = (*env)->NewStringUTF(env, url);
     const int ret = (*env)->CallStaticIntMethod(env, mActivityClass, midOpenURL, jurl);