Fix bootstrap.
Merge topic 'minor-cleanups' into next

337d2df Fix bootstrap.
Don't allow include() of export(EXPORT) file at configure time.

As a new feature it does not need to participate in CMP0024.

Store cmExportBuildFileGenerator instances which correspond to the
export(EXPORT) signature in a second map which does not own the
pointers.  This avoids the need to add cmExportBuildFileGenerator
and dependencies to the bootstrap system.
Merge topic 'minor-cleanups' into next

8b9afc9 Don't allow include() of export(EXPORT) file at configure time.