This commit fixed two bugs when one client reset the connection.
The first is that we should reopen the graphic device when the previous
node was closed during the screen closing. The second one is we should
call glamor_close_screen (not the ddx version) prior to call
eglTerminate(). As eglTerminate will release the share library. And
the glamor_close_screen may still need to call openGL APIs and thus
will hit segfault. And renamed the ddx functions to avoid naming
conflications with the glamor functions.
GC is redefined in the X11/Xlib.h and include/gcstruct.h which is
a xorg header file. Just use a macro to simply avoid the conflict.
Need revisit latter to find a correct way to fix this problem.