in-Portfile variant removal (not default)?

[Michael Dickens]

After playing around with Qt, QCA, & QCA plugins (QCA-OSSL & such), it's
clear to me that while Qt -allows- one to install just a debug library
(though not as a framework), it's not a good idea to do so.  None of the
qmake include files (e.g., for QCA) that I've read through are written
for that scenario -- they all depend on at least the release library
being available (as a framework or just library; doesn't matter).  So,
my original question is moot and I'll be modifying the Qt & related
Portfiles so that there is no issue -- either install release or
release-and-debug, but not  debug only.  This change simplifies the
Portfiles a bit as well as removes the issue. - MLD