defined via Mk/bsd.default-versions.mk which has moved from GCC 7.4 t
GCC 8.2 under most circumstances.

This includes ports
 - with USE_GCC=yes or USE_GCC=any,
 - with USES=fortran,
 - using Mk/bsd.octave.mk which in turn features USES=fortran, and
 - with USES=compiler specifying openmp, nestedfct, c11, c++0x, c++11-lang,
   c++11-lib, c++14-lang, c++17-lang, or gcc-c++11-lib
plus, as a double check, everything INDEX-11 showed depending on lang/gcc7.

PR:		231590

  Ports using USE_PYTHON=distutils are now flavored.  They will
  automatically get flavors (py27, py34, py35, py36) depending on what
  versions they support.

  There is also a USE_PYTHON=flavors for ports that do not use distutils
  but need FLAVORS to be set.  A USE_PYTHON=noflavors can be set if
  using distutils but flavors are not wanted.

  A new USE_PYTHON=optsuffix that will add PYTHON_PKGNAMESUFFIX has been
  added to cope with Python ports that did not have the Python
  PKGNAMEPREFIX but are flavored.

  USES=python now also exports a PY_FLAVOR variable that contains the
  current python flavor.  It can be used in dependency lines when the
  port itself is not python flavored.  For example, deskutils/calibre.

  By default, all the flavors are generated.  To only generate flavors
  for the versions in PYTHON2_DEFAULT and PYTHON3_DEFAULT, define
  BUILD_DEFAULT_PYTHON_FLAVORS in your make.conf.

  In all the ports with Python dependencies, the *_DEPENDS entries MUST
  end with the flavor so that the framework knows which to build/use.
  This is done by appending '@${PY_FLAVOR}' after the origin (or
  @${FLAVOR} if in a Python module with Python flavors, as the content
  will be the same).  For example:

    RUN_DEPENDS= ${PYTHON_PKGNAMEPREFIX}six>0:devel/py-six@${PY_FLAVOR}

PR:		223071
Reviewed by:	portmgr, python
Sponsored by:	Absolight
Differential Revision:	https://reviews.freebsd.org/D12464

With hat:	portmgr
Sponsored by:	Absolight