fix Issue 13613 - Pragma msg affects data structure layout
Merge pull request #4106 from 9rnsr/fix13613

Issue 13613 - Pragma msg affects data structure layout
Store config filename in global object.
Show config file if object.d can't be found.

To help troubleshoot problems caused by stray copies of dmd.conf
(see bugzilla issue 4567).
Print config file being used in usage().
Merge pull request #4108 from quickfur/issue4567

Issue 4567: display dmd.conf path being used if object.d can't be found