libsysdecode: add explicit dependencies on recently changed headers

r349369 removed IP_MIN_MEMBERSHIPS and IPV6_MIN_MEMBERSHIPS, and r349893
removed TCP_RACK_SESS_CWV. libsysdecode lacked dependencies to trigger a
rebuild of tables.h.

Add explicit dependencies as a workaround to address these specific
cases; a holistic solution is still needed.

Sponsored by:	The FreeBSD Foundation

lib/libsysdecode/Makefile

@@ -123,7 +123,8 @@ CFLAGS.gcc.ioctl.c+= -Wno-redundant-decls
 CFLAGS.gcc+=	${CFLAGS.gcc.${.IMPSRC}}
 
 DEPENDOBJS+=	tables.h
-tables.h: mktables
+tables.h: mktables ${SYSROOT}/sys/netinet/in.h ${SYSROOT}/sys/netinet/tcp.h \
+    ${SYSROOT}/sys/netinet6/in6.h
 	sh ${.CURDIR}/mktables ${SYSROOT:U${DESTDIR}}${INCLUDEDIR} ${.TARGET}.tmp && \
 	    mv -f ${.TARGET}.tmp ${.TARGET}