This function adds support for buildconfig and installconfig
Works basically the same way FILES except that installconfig is not hooked to
the realinstall target
Convert the distribution target to keep the current behaviour and call
installconfig on every directories
so mergemaster and friends keep working as expected
Move dma.conf into the libexec/dma directory where it belongs.
This helps packaging base so that when a Makefile is tagged to belong to a given
package all its configuration files are also tagged correctly
It also makes confiuration files behaving like other files: includes, manpages,
etc