XCB/X11: pre-allocate and reuse shared memory segment XID
XCB/X11: pre-allocate and reuse shared memory segment XID

The X server supplies a large but nevertheless finite range of XID for
the X client to use. So lets reuse our handles.

vlc-mirror/vlc,vlc-mirror/vlc,krichter722/vlc,krichter722/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,xkfz007/vlc,krichter722/vlc,krichter722/vlc,krichter722/vlc,xkfz007/vlc,jomanmuk/vlc-2.2,xkfz007/vlc,vlc-mirror/vlc,krichter722/vlc,shyamalschandra/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,shyamalschandra/vlc,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc,vlc-mirror/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,vlc-mirror/vlc