x11-toolkits/wlroots-devel: unbreak on FreeBSD < 13 after 0efbfe7

../render/gles2/renderer.c:561:16: error: use of undeclared identifier 'CLOCK_MONOTONIC'
        clock_gettime(CLOCK_MONOTONIC, &timer->cpu_start);
                      ^

x11-toolkits/wlroots-devel/Makefile

@@ -75,5 +75,12 @@ post-patch:
 # Extract (snapshot) version from the port instead of meson.build
 	@${REINPLACE_CMD} "/STR/s/meson.project_version()/'${DISTVERSIONFULL}'/" \
 		${WRKSRC}/include/wlr/meson.build
+# XXX Drop after FreeBSD 12.4 EOL around 2023-12-31
+# https://cgit.freebsd.org/src/commit/?id=d7535fb3e3cb
+	@if [ ${OPSYS} = FreeBSD -a ${OSVERSION} -lt 1300515 ]; then \
+		${REINPLACE_CMD} -e '/POSIX/s/199309/200112/' \
+		${WRKSRC}/render/gles2/pass.c \
+		${WRKSRC}/render/gles2/renderer.c; \
+	fi
 
 .include <bsd.port.mk>