Remove COPYING-panoramixproto

panoramixproto never had any real content, that was all in xineramaproto
instead.

COPYING-panoramixproto

-This is a stub file.  This package has not yet had its complete licensing
-information compiled.  Please see the individual source files for details on
-your rights to use and modify this software.
-
-Please submit updated COPYING files to the Xorg bugzilla:
-
-https://bugs.freedesktop.org/enter_bug.cgi?product=xorg
-
-All licensing questions regarding this software should be directed at the
-Xorg mailing list:
-
-http://lists.freedesktop.org/mailman/listinfo/xorg

Makefile.am

@@ -481,7 +481,6 @@ EXTRA_DIST = \
     COPYING-inputproto \
     COPYING-kbproto \
     COPYING-lg3dproto \
-    COPYING-panoramixproto \
     COPYING-pmproto \
     COPYING-presentproto \
     COPYING-printproto \