* gnu/packages/video.scm (avidemux)[source]: Add patch to install to lib
directory instead of lib64 or lib32 depending on the architecture.
[arguments]: Use the lib instead of the lib64 directory for flags in the
build phase, so that these flags should now also work on i686.
* gnu/packages/patches/avidemux-install-to-lib.patch: New file.
* gnu-system.am (dist_patch_DATA): Register it.
