remove duplicate aviplay.c in Windows Phone project

winrt/SDLPal.WindowsPhone/SDLPal.Core.vcxproj

@@ -305,7 +305,6 @@
     <ClCompile Include="..\..\liboggvorbis\src\window.c" />
     <ClCompile Include="..\..\magicmenu.c" />
     <ClCompile Include="..\..\main.c" />
-    <ClCompile Include="..\..\aviplay.c" />
     <ClCompile Include="..\..\map.c" />
     <ClCompile Include="..\..\midi.c" />
     <ClCompile Include="..\..\mp3play.c" />