1. Moved all the PNETCDF code
   (primarily from libsrc4)
   into its own dispatch library
   called libsrc5.

2. Fixed part of Jira NCF-253
   by removing the need for the
   pnetcdf_ndims field.
   For some reason, the original
   code tried to cache the variable
   ranks rather than computing them
   as needed. Fixed by doing
   an ...inq_varndims call as needed.

3. found some places where NC_MAX_DIMS
   was being stack allocated and changed
   to heap allocation.
   Still some cases in nc_test4.






git-svn-id: https://sub.unidata.ucar.edu/netcdf/trunk@3232 2e3060e4-1ed8-cf1f-9cc2-9586e844a556