Added missing(?) include of bamWriter.h; please undo if this causes problems.

panda/src/grutil/movieTexture.cxx

@@ -24,6 +24,7 @@
 #include "config_grutil.h"
 #include "bamCacheRecord.h"
 #include "bamReader.h"
+#include "bamWriter.h"
 #include "math.h"
 #include "audioSound.h"