Make auto-generated ioctl.c to be always considered out of date

since it could potentially depend on any ${DESTDIR}/usr/include
preprocessor file.  This fixes the broken -DNOCLEAN world build
I experienced yesterday.

usr.bin/kdump/Makefile

@@ -7,7 +7,7 @@ SRCS=	kdump.c ioctl.c subr.c
 .PATH:	${.CURDIR}/../ktrace
 CLEANFILES+=ioctl.c
 
-ioctl.c: mkioctls
+ioctl.c: .PHONY
 	sh ${.CURDIR}/mkioctls ${DESTDIR}/usr/include > ioctl.c
 
 .include <bsd.prog.mk>

usr.bin/truss/Makefile

@@ -28,7 +28,7 @@ syscalls.h:	syscalls.master
 	/bin/sh ${.CURDIR}/../../sys/kern/makesyscalls.sh syscalls.master \
 		${.CURDIR}/i386.conf
 
-ioctl.c:	${.CURDIR}/../../usr.bin/kdump/mkioctls
+ioctl.c:	.PHONY
 	sh ${.CURDIR}/../../usr.bin/kdump/mkioctls ${DESTDIR}/usr/include > ioctl.c
 
 .include <bsd.prog.mk>