java/openjdk11: add new CUPS port option

UniFi controller is headless Java application that requires
OpenJDK that depends on full CUPS port. In fact, the latter originally
required cups-client port only that was later removed and merged
to full cups port, so openjdk11 now requires full CUPS.

However, OpenJDK really needs only some header files out of CUPS distribution
and officially supports building --with-cups-include instead of --with-cups.

This change introduces new CUPS port option to java/openjdk11
that defaults to ON to preserve current behaviour.
With CUPS option turned OFF it skips build dependency on full cups:
instead, it downloads and extracts its distfile and
builds --with-cups-include pointing to extracted cups distfile.

Default build not affected, so PORTREVISION not changed.

PR:		264792
Approved by:	java (maintainer timeout, over 7 months)