Simplify FORTRAN access to the new plugin path mechanism

[DennisHeimbigner]

The new plugin path API uses char** to represent a variable lenght vector of variable length strings. FORTRAN is not capable of accessing such structures. So, this PR extends the API to provide a counted string-based API to the plugin path functionality.

The new functions are inserted in the netcdf_aux.h/daux.c files. The new functions are just wrappers around other plugin path API function; they are just (I hope) more convenient for FORTRAN users. The new functions are as follows:

ncaux_plugin_path_stringlen(void)

• Return the length (as in strlen) of the current plugin path directories encoded as a string. Return -1 if the request fails.

int ncaux_plugin_path_stringget(int pathlen, char path)*

• Get the current sequence of directories in the internal global plugin path list encoded as a string path using ';' as a path separator. As an example, it might return "/a/b/c;/home/user/me;/tmp". The arguments are as follows:
  • pathlen -- the length of the path argument.
  • path -- a string into which the current plugin path as a string is stored.
• Return NC_NOERR | NC_EINVAL

int ncaux_plugin_path_stringset(int pathlen, const char path)*

• Set the current sequence of directories in the internal global plugin path list. As an example, it might take "/a/b/c;/home/user/me;/tmp". The arguments are as follows:
  • pathlen -- the length of the path argument.
  • path -- a string that is parsed to obtain the sequence of directories for the current plugin path.
• Return NC_NOERR | NC_EINVAL