• build with IMAP and POP support when PACKAGE_BUILDING (because that was default before adding the WITH_MUTT_IMAP and WITH_MUTT_POP knobs).

• fix pkg-plist if not build with WITH_MUTT_IMAP or WITH_MUTT_POP.

• rename internal variable to less confusing name

Submitted by: Udo Schweigert <ust@cert.siemens.de>