vulkan/wsi: add support for detecting mit-shm pixmaps.

This just adds the xcb bits to detect is the host supports shared
shm pixmaps or whether the old paths should be used.

shm pixmaps will only be used if dri3 is available

Acked-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12482>

meson.build

@@ -1963,7 +1963,6 @@ if with_platform_x11
     dep_xext = dependency('xext')
     dep_xfixes = dependency('xfixes', version : '>= 2.0')
     dep_xcb_glx = dependency('xcb-glx', version : '>= 1.8.1')
-    dep_xcb_shm = dependency('xcb-shm')
   endif
   if (with_any_vk or with_glx == 'dri' or with_egl or
        (with_gallium_vdpau or with_gallium_xvmc or with_gallium_va or
@@ -1986,6 +1985,7 @@ if with_platform_x11
           dep_xcb_present.version().version_compare('>= 1.13'))
         pre_args += '-DHAVE_DRI3_MODIFIERS'
       endif
+      dep_xcb_shm = dependency('xcb-shm')
       dep_xcb_sync = dependency('xcb-sync')
       dep_xshmfence = dependency('xshmfence', version : '>= 1.1')
     endif