drisw: Port the MIT-SHM check to XCB

The old version isn't thread-safe, and xlib makes it unreasonably
difficult to write thread-safely.

Fixes: mesa/mesa#3398
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6294>
diff --git a/meson.build b/meson.build
index db4f8fc..2478753 100644
--- a/meson.build
+++ b/meson.build
@@ -1701,6 +1701,7 @@
 dep_xcb_xfixes = null_dep
 dep_xshmfence = null_dep
 dep_xcb_xrandr = null_dep
+dep_xcb_shm = null_dep
 dep_xlib_xrandr = null_dep
 if with_platform_x11
   if with_glx == 'xlib' or with_glx == 'gallium-xlib'
@@ -1713,6 +1714,7 @@
     dep_xdamage = dependency('xdamage', version : '>= 1.1')
     dep_xfixes = dependency('xfixes')
     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