Do not build transform video filter plugin.

It will have to be converted to "video filter2" (and the core extended
to support output format changes).

modules/video_filter/Modules.am

@@ -112,7 +112,6 @@ libvlc_LTLIBRARIES += \
 	libscale_plugin.la \
 	libscene_plugin.la \
 	libsharpen_plugin.la \
-	libtransform_plugin.la \
 	libwall_plugin.la \
 	libwave_plugin.la \
 	libyuvp_plugin.la