configure.ac: Check for libdvdnav to build resindvd.

configure.ac: Check for libdvdnav to build resindvd.

Original commit message from CVS:
* configure.ac:
Check for libdvdnav to build resindvd.
* ext/Makefile.am:
* ext/resindvd/Makefile.am:
* ext/resindvd/gstmpegdefs.h:
* ext/resindvd/gstmpegdemux.c:
* ext/resindvd/gstmpegdemux.h:
* ext/resindvd/gstmpegdesc.c:
* ext/resindvd/gstmpegdesc.h:
* ext/resindvd/gstpesfilter.c:
* ext/resindvd/gstpesfilter.h:
* ext/resindvd/plugin.c:
* ext/resindvd/resin-play:
* ext/resindvd/resindvdbin.c:
* ext/resindvd/resindvdbin.h:
* ext/resindvd/resindvdsrc.c:
* ext/resindvd/resindvdsrc.h:
* ext/resindvd/rsnaudiomunge.c:
* ext/resindvd/rsnaudiomunge.h:
* ext/resindvd/rsnbasesrc.c:
* ext/resindvd/rsnbasesrc.h:
* ext/resindvd/rsnpushsrc.c:
* ext/resindvd/rsnpushsrc.h:
* ext/resindvd/rsnstreamselector.c:
* ext/resindvd/rsnstreamselector.h:
First commit of DVD-Video playback component 'rsndvdbin'
and helper elements.
Use --enable-experimental for now, but feel free to give it a
try using the resin-play script.
* gst/dvdspu/gstdvdspu.c:
Add some extra guards for malformed events.