Re: WIP Incremental JSON Parser

Coverity complained that this patch leaks memory:

/srv/coverity/git/pgsql-git/postgresql/src/bin/pg_combinebackup/load_manifest.c: 212 in load_backup_manifest()
206                 bytes_left -= rc;
207                 json_parse_manifest_incremental_chunk(
208                                                       inc_state, buffer, rc, bytes_left == 0);
209             }
210
211             close(fd);
>>>     CID 1596259:    (RESOURCE_LEAK)
>>>     Variable "inc_state" going out of scope leaks the storage it points to.
212         }
213
214         /* All done. */
215         pfree(buffer);
216         return result;
217     }

/srv/coverity/git/pgsql-git/postgresql/src/bin/pg_verifybackup/pg_verifybackup.c: 488 in parse_manifest_file()
482                 bytes_left -= rc;
483                 json_parse_manifest_incremental_chunk(
484                                                       inc_state, buffer, rc, bytes_left == 0);
485             }
486
487             close(fd);
>>>     CID 1596257:    (RESOURCE_LEAK)
>>>     Variable "inc_state" going out of scope leaks the storage it points to.
488         }
489
490         /* Done with the buffer. */
491         pfree(buffer);
492
493         return result;

It's right about that AFAICS, and not only is the "inc_state" itself
leaked but so is its assorted infrastructure.  Perhaps we don't care
too much about that in the existing applications, but ISTM that
isn't going to be a tenable assumption across the board.  Shouldn't
there be a "json_parse_manifest_incremental_shutdown()" or the like
to deallocate all the storage allocated by the parser?

            regards, tom lane