Update FindFFmpeg to find/search for libswscale

[Alexander Neundorf]

On Monday 10 May 2010, Christoph Feck wrote:
> Hello,
>
> For the upcoming FFmpeg based thumbnailer, we need the libswscale library
> that is part of the FFmpeg project.
>
> The FindFFmpeg.cmake in kdelibs does, however, not handle that library.
> Could somebody with knowledge of cmake voodoo update that file? It would
> be nice if an additional HAVE_SWSCALE is added to the results.

Basically it should boil down to a find_library() call.
Instead of HAVE_SWSCALE the more cmake-style result would be a 
FFMPEG_SWSCALE_LIBRARY variable, which you can then test for.

>
> Possible candidates to look at are
> http://websvn.kde.org/trunk/kdesupport/strigi/libstreamanalyzer/cmake/FindF
>FMPEG.cmake?view=markup and

The if(FALSE) in this file are _most_ probably wrong.
Also the NO_DEFAULT_PATH should not be necessary, instead "HINTS" probably 
should be used instead of "PATHS".
It should use find_package_handle_standard_args().

Can you give it a try and polish this file up a bit ?
Then it can be used also for your thumbnailer I guess.

Alex