Update databases/mongo-c-driver to 1.3.0.

pkgsrc changes:
- Release tarballs cannot build man pages any more, use pre-built
  ones instead.

Changes since 1.2.1:

- If the driver is compiled without SSL support but a URI with "ssl=true"
  is passed to mongoc_client_new, mongoc_client_new_from_uri, or
  mongoc_client_pool_new, the function logs an error and returns NULL.
  Before, the driver would attempt a non-SSL connection.
- mongoc_collection_find_and_modify will now apply the mongoc_collection_t's
  write_concern_t when talking to MongoDB 3.2.
- Support for MongoDB 3.2's "readConcern" feature for queries, counts,
  and aggregations. The option "readConcernLevel" is now accepted in
  the MongoDB URI.
- Support for MongoDB 3.2's "bypassDocumentValidation" option for writes.
- New struct mongoc_bulk_write_flags_t and related functions.
- New struct mongoc_find_and_modify_opts_t and related functions.
- New functions to copy database and collection handles.
- Support for MongoDB 3.2 wire protocol: use commands in place of OP_QUERY,
  OP_GETMORE, and OP_KILLCURSORS messages.
- To explain a query plan with MongoDB 3.2, you must now call the "explain"
  command, instead of including the "$explain" key in
  a mongoc_collection_find query. See the mongoc_collection_find
  documentation page for details.
- Configurable wait time on tailable cursors with MongoDB 3.2.
- Use electionId to detect a stale replica set primary during
  a network split.
- Disconnect from replica set members whose "me" field does not match
  the connection address.
- The client side matching feature, mongoc_matcher_t and related functions,
  are deprecated and scheduled for removal in version 2.0.
- New CMake options ENABLE_SSL, ENABLE_SASL, ENABLE_TESTS, and
  ENABLE_EXAMPLES.
- Use constant-time comparison when verifying credentials.
- Combine environment's CFLAGS with configure options when building.
- Improved man page output and "whatis" entries.

(fhajny)