Updated SDL2 to the latest Mercurial revision.

libs/SDL2/visualtest/COPYING.txt

@@ -15,4 +15,4 @@ freely, subject to the following restrictions:
    appreciated but is not required.
 2. Altered source versions must be plainly marked as such, and must not be
    misrepresented as being the original software.
-3. This notice may not be removed or altered from any source distribution.
+3. This notice may not be removed or altered from any source distribution.

libs/SDL2/visualtest/unittest/testquit.c

@@ -98,4 +98,4 @@ main(int argc, char** argv)
     }
 
     return exit_code;
-}
+}