build: manually check for dirty repo
build: manually check for dirty repo

The --dirty option was added to "git describe" in
v1.6.5-1-g9f67d2e (Wed Oct 21 09:35:22 2009). To support git
versions before this the dirty check is implemented using the same
method as git describe. The --dirty option is not used.

ebu/ebu-libmxfpp,ebu/ebu-libmxfpp,stuarthicks/libmxfpp,stuarthicks/libmxfpp,Limecraft/ebu-libmxfpp,ebu/ebu-libmxfpp,Limecraft/ebu-libmxfpp,Limecraft/ebu-libmxfpp,stuarthicks/libmxfpp