Restore PictStandardA4

[Po Lu]

Emacs uses the PictStandardA4 picture format to display certain kinds of
images.  A "painfully slow" software fallback is not a problem, since
the important thing is for the picture to be displayed in the first
place.

So there are "users in the wild", and in any case the X.Org server
should hold itself to its own protocol specifications.  Thus, as an
Emacs developer, I'd like to ask for:

  https://gitlab.freedesktop.org/xorg/xserver/-/commit/436fd7e8b4966c305ea9c43f3c14c2ca04c35539

to be reverted, or for a major version bump of the rendering extension.
That commit came as a nasty surprise when I updated my local X server.

Backwards incompatible changes should *NOT* be made out of the blue.  No
matter how many applications you look at, you will always miss one or
two.  And there may be private code, or code someone will write in the
future.  "All the major toolkits and libXft" do *NOT* cover every
application in the wild, especially not Emacs, whose X Windows code
predates all of those libraries and toolkits and refrains from relying
on any them.  I cannot stress that enough.  Emacs has never needed to
deal with X servers breaking backwards compatibility in the past and it
would be a shame for that to start now.

They should be made in accordance with what renderproto.txt says:

	Major versions changes can introduce incompatibilities in
	existing functionality, minor version changes introduce only
	backward compatible changes.