the dev branch builds just fine even if 2.8.16 is also installed
just fallow the instructions on the wiki
using autotools "config.site"
-- a bit old but works
http://wiki.gimp.org/wiki/Hacking:Building/Linux
and
http://lightningismyname.blogspot.co...ling-gimp.html
there is a handy "install-config-site.sh" that will set up the autotools "config.site" file
then to run just make a small script to EXPORT the
export PATH="?????:$PATH"
export PKG_CONFIG_PATH="?????:$PKG_CONFIG_PATH"
export LD_LIBRARY_PATH="?????:$LD_LIBRARY_PATH"
and run the new gimp binary