community/dcc: stop installing files to /var

For some reason this package was installing all kinds of binaries to /var/dcc/libexec, even though /var is meant for "variable data files". https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch05.html#purpose31

Architecture specific files are supposed to go to different directories, libexec for example should go to /usr/libexec. https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch04s07.html