NC4_inq_type_equal() does not check return code of H5Tequal()

[edhartnett]

In function NC4_inq_type_equal(), there is this code:

   /* Are the two types equal? */
   if (equalp)
      *equalp = (int)H5Tequal(type1->native_hdf_typeid, type2->native_hdf_typeid);

However, when H5Tequal() returns an error (-1) hilarious confusion will ensue.

The return value of H5Tequal() needs to be checked, and NC_EHDFERR returned if it fails.

Note that in these cases, nc_inq_type_equal() will get an incorrect result, -1, which the user will interpret as equal.