re: Issue https://github.com/Unidata/netcdf-c/issues/2502
H/T Charlie Zender
* Fix NCZarr handling of endianness value NC_ENDIAN_NATIVE. This now matches how it is handled in libhdf5
* Fix NCZarr handling of char typed attribute with value "". This now matches how it is handled in libhdf5
* Add test for various char attribute values
* Change the mapping of NC_CHAR and NC_STRING to dtype; requires changing some test files also.
* Optimize the testing for NC_ENOTBUILT in NC_open.
* Turn off debugging left on accidentally
* Fix memory leak in tst_pnetcdf.c
* Fix blosc test
