xvba: fix newphreak segfault with Shared Surfaces disabled.

XVBA::Present does not secure render enough. If NOT (outPic AND NOTisDuplicate)
the outPic is set, but the render stays potentially NuLL. Which brings CopyYV12 to segfault
as render is not checked for !NULL

Only set outPic if render present?

xbmc/cores/dvdplayer/DVDCodecs/Video/XVBA.cpp

@@ -1231,7 +1231,17 @@ void CDecoder::CopyYV12(int index, uint8_t *dest)
 
   if (!m_flipBuffer[index].outPic)
   {
-    CLog::Log(LOGWARNING, "XVBA::Present: present picture is NULL");
+    CLog::Log(LOGWARNING, "XVBA::CopyYV12: current picture is NULL");
+    return;
+  }
+  if (!m_flipBuffer[index].outPic->render)
+  {
+    CLog::Log(LOGWARNING, "XVBA::CopyYV12: current render is NULL");
+    return;
+  }
+  if (!m_flipBuffer[index].outPic->render->surface)
+  {
+    CLog::Log(LOGWARNING, "XVBA::CopyYV12: current surface is NULL");
     return;
   }
 
@@ -1252,7 +1262,7 @@ void CDecoder::CopyYV12(int index, uint8_t *dest)
   { CSingleLock lock(m_apiSec);
     if (Success != g_XVBA_vtable.GetSurface(&input))
     {
-      CLog::Log(LOGERROR,"(XVBA::CopyYV12) failed to get  surface");
+      CLog::Log(LOGERROR,"XVBA::CopyYV12: failed to get surface");
     }
   }
 }