graphics/cairo: drop xorgproto from OPENGL

X11 already depends on xorgproto while GLX requires X11.

$ pkg info -ql xorgproto | sed '/include/!d; s,.*include/,,' |

fgrep --exclude='*config*' --exclude='*ChangeLog*' -rnf - .

./boilerplate/cairo-boilerplate-glx.c:37:#include <X11/X.h>
./src/cairo-xlib-surface-shm.c:145:#include <X11/Xproto.h>
./src/cairo-xlib-surface-shm.c:148:#include <X11/extensions/shmproto.h>
./src/cairo-xlib-surface-shm.c:150:#include <X11/extensions/shmstr.h>
./src/cairo-xlib-xrender-private.h:56:#include <X11/extensions/renderproto.h>
./src/cairo-xlib-xrender-private.h:219:/* Copied from X11/extensions/render.h */
./src/cairo-xlib-xrender-private.h:533:/* Copied from X11/extensions/renderproto.h */
./src/cairo-xlib-xrender-private.h:535:#include <X11/Xmd.h>

Submitted by: manu (based on)