Fix a build error with OpenMPI 1.4.x

The function ADIOI_PLFS_Feature() shouldn't be defined when
compiling PLFS with OpenMPI 1.4.x.
re-added 1-n information to plfsrc.5in that was accidently removed in an earlier merge
Merge branch '2.4dev' of github.com:agtorre/plfs-core into 2.4dev