Avidemux: Update to 2.6.20 and misc changes

[bgrupe27]

Hi,

avidemux is pretty outdated and I started to work on updating it to 2.6.20.

The portfile diff is attached. One error occurs during build regarding to x264:

{{{CMake Error at /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_multimedia_avidemux/avidemux/work/destroot/opt/local/include/avidemux/2.6/cmake/admCheckX264.cmake:24 (ELSE):

A duplicate ELSE command was found inside an IF block.

Call Stack (most recent call first):

ADM_videoEncoder/x264/CMakeLists.txt:12 (checkX264)

}}}

A quick fix would be the attached diff, would that be acceptable?

[bgrupe27]

Portfile diff

[bgrupe27]

x264 diff