Fix disabling libxcb-shm and libxcb-xfixes.

configure

@@ -5030,15 +5030,15 @@ if ! disabled libxcb; then
     } && disable x11grab && enable libxcb
 
 if enabled libxcb; then
-    disabled libxcb_shm ||
+    disabled libxcb_shm || {
         check_pkg_config xcb-shm xcb/shm.h xcb_shm_attach || {
             enabled libxcb_shm && die "ERROR: libxcb_shm not found";
-        } && check_header sys/shm.h && enable libxcb_shm
+        } && check_header sys/shm.h && enable libxcb_shm; }
 
-    disabled libxcb_xfixes ||
+    disabled libxcb_xfixes || {
         check_pkg_config xcb-xfixes xcb/xfixes.h xcb_xfixes_get_cursor_image || {
             enabled libxcb_xfixes && die "ERROR: libxcb_xfixes not found";
-        } && enable libxcb_xfixes
+        } && enable libxcb_xfixes; }
 
     add_cflags "$xcb_event_cflags $xcb_shm_cflags $xcb_xfixes_cflags"
     add_extralibs "$xcb_event_libs $xcb_shm_libs $xcb_xfixes_libs"