deinterlace: tomsmocomp SSE2 code disabled because IS_SSE2 is never defined anywhere

In this line:

https://gitlab.freedesktop.org/gstreamer/gst-plugins-good/-/blob/master/gst/deinterlace/tvtime/tomsmocomp/tomsmocompmacros.h#L62

there is:

#ifdef IS_SSE2

but this doesn't seem to be defined anywhere, effectively disabling the SSE2 code.