YAXT

• reduces libtool compatibility headaches with the new nvfortran compiler,
• fixes a small memory leak when more than 8 redists are used to form a collection,
• fixes an incorrect computation of position extents when an xmap is constructed manually,
• hides internal library symbols,
• fixes the passing of zero size arrays in the Fortran interface,
• add minor improvements to the cfortran.h header.

Also see commit log at commit:f2eb603483f3b8041.