xcb: Use QT_CONFIG macro to check for xcb-xlib

... and remove the XCB_USE_XLIB define.

This patch also removes the unnecessary checks for xcb-xlib in:

- qxcbglxintegration.cpp as this files is build _only_ when
xcb-xlib is present. From gl_integrations.pro:

 qtConfig(xcb-xlib):qtConfig(opengl):!qtConfig(opengles2) {
    SUBDIRS += xcb_glx
 }

This also would have been the right place where to define
XCB_USE_XLIB, instead of unconditional line in xcb_glx.pro:

 DEFINES += XCB_USE_GLX XCB_USE_XLIB

- qxcbnativeinterface.cpp as this cpp file does not use any
Xlib APIs directly, there is no need to include Xlib.h.

Change-Id: I531b5f1e79606fcfd1c63810cf51b7d5e9dc58a7
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

0 files changed, 0 insertions, 0 deletions