bugfix: mmjsonparse did not build with json-c < 0.10

This was a regression introduced some time in the past in order to
support API changes in json-c. Now we check for the version and use
proper code.

Conflicts:

	ChangeLog
Merge branch 'v7-stable' of git+ssh://git.adiscon.com/git/rsyslog into v7-stable
Merge branch 'v7-stable' into v8-stable
bugfix: build failure on systems which don't have json_tokener_errors

Older versions of json-c need to use a different API (which don't exists
on newer versions, unfortunately...)
Thanks to Thomas D. for reporting this problem.