Otherwise, it means the X11 compositor depends on another library to
pull xcb-shm (cairo?), which is not always the case. Here I end up with:
[01:54:38.970] Failed to load module:
$prefix/lib/weston/x11-backend.so: undefined symbol: xcb_shm_id
LIBS=$xcb_save_LIBS
CFLAGS=$xcb_save_CFLAGS
- X11_COMPOSITOR_MODULES="x11 x11-xcb"
+ X11_COMPOSITOR_MODULES="x11 x11-xcb xcb-shm"
PKG_CHECK_MODULES(X11_COMPOSITOR_XKB, [xcb-xkb],
[have_xcb_xkb="yes"], [have_xcb_xkb="no"])