Comment 4 for bug 1908305

I now realize that it's only registerRecordDeviceDriver.pl which should allow auto-declaration of record types; dbdExpand.pl should throw an error if the parser sees a device support reference to a record type that doesn't exist. This means no build-system flag should be required for building device support into a loadable module, which simplifies the fix to Perl code changes only.

I have closed the previous PR and created https://github.com/epics-base/epics-base/pull/112 with this approach instead.