compositor-x11: Only use xcb_poll_for_queued_event if we have it
Otherwise we can just fall back to xcb_poll_for_event, and just do a
harmless read on the socket.
diff --git a/configure.ac b/configure.ac
index 8873bd0..8c5a8af 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,6 +21,15 @@
PKG_PROG_PKG_CONFIG()
+PKG_CHECK_MODULES([XCB], xcb)
+xcb_save_LIBS=$LIBS
+xcb_save_CFLAGS=$CFLAGS
+CFLAGS=$XCB_CFLAGS
+LIBS=$XCB_LIBS
+AC_CHECK_FUNCS([xcb_poll_for_queued_event])
+LIBS=$xcb_save_LIBS
+CFLAGS=$xcb_save_CFLAGS
+
AC_CHECK_FUNC([dlopen], [],
AC_CHECK_LIB([dl], [dlopen], DLOPEN_LIBS="-ldl"))
AC_SUBST(DLOPEN_LIBS)