From Bertrand:
the new gfal has now a dependency on a package called srm-ifce. Add flag
to specify the location of the gfal_srm_ifce_types.h header.


git-svn-id: https://root.cern.ch/svn/root/trunk@48518 27541ba8-7e3a-0410-8455-c3a389f83636