graphics/mesa-libs: Bump reverse deps for libglvnd

Per discussion with bapt on helping pkg handle the changing of these
deps and avoiding impossible upgrade senarios.

PR:		246767
Reviewed by:	manu, bapt
Approved by:	x11
Differential Revision:	https://reviews.freebsd.org/D30824

Remove # $FreeBSD$ from Makefiles.

Drop python 2.7 support from a few ports

With hat:	portmgr

graphics/py-PyOpenGL and graphics/py-PyOpenGL-accelerate: Update to 3.1.5.

Differential Revision:	https://reviews.freebsd.org/D23743

Convert the tree to use PY_PILLOW

With hat:	portmgr
Originally submitted by:	kai

graphics/py-pillow: Update to 7.0.0

* Repo-Copy the Pillow 6.2.2 release to graphics/py-pillow6 to retain
  backwards compatibility for Python 2 consumers as the Pillow 7.0.0 release
  dropped the support for Python 2.

* Apply conditional statements to use either Pillow 7.x or Pillow 6.x for
  consumers that can be built for Python 2 or newer.

* Exceptions are ports that can be built only for either Python 2 or
  Python 3.  For the first case, consumers are just assigned to the
  repo-copied graphics/py-pillow6.

* Also remove Pillow from BUILD_DEPENDS of math/py-PyWavelets as it is not
  listed in setup.py as a build dependency [1] and relax the version

Add USES=xorg USES=gl, ports categories g

Add USES=xorg and USES=gl to ports in categories starting with 'g'.
While here, try to sprinkle other USES (mostly gnome and sdl) as needed.

Bump PORTREVISION for ports depending on the canonical version of GCC
as defined in Mk/bsd.default-versions.mk which has moved from GCC 8.3
to GCC 9.1 under most circumstances now after revision 507371.

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, everything INDEX-11 shows with a dependency on lang/gcc9 now.

PR:		238330

Bump PORTREVISION for ports depending on the canonical version of GCC
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

Use PY_FLAVOR for dependencies.

FLAVOR is the current port's flavor, it should not be used outside of
this scope.

Sponsored by:	Absolight

Bump PORTREVISIONs of all users of math/mpc that we just updated to
version 1.1.0 (via revision 464079).

Convert Python ports to FLAVORS.

  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

Revision bump of all ports with USE_GL after consolidation of mesa-libs

Approved by:	swills (mentor)
Differential Revision:	https://reviews.freebsd.org/D10845

graphics/py-opengl{-accelerate}: 3.0.1 -> 3.1.0, change to PyPI naming

- upgrade fixes the use of the port
- py-opengl -> py-PyOpenGL
- py-opengl-accelerate -> py-PyOpenGL-accelerate

PR:		205472
Submitted by:	matthew@reztek.cz
Reviewed by:	koobs