Use FILES for installing the dtrace scripts.

The BSD.usr.dist mtree always creates /usr/lib/dtrace so there is no
need to check if it exists.

The FILES mechanism already supports LIBRARIES_ONLY.

Sponsored by:	EMC / Isilon Storage Division

cddl/lib/libdtrace/Makefile

@@ -56,6 +56,10 @@ DSRCS=		errno.d			\
 		udp.d			\
 		unistd.d
 
+FILES=		${DSRCS}
+FILESDIR=	/usr/lib/dtrace
+FILESMODE=	${NOBINMODE}
+
 WARNS?=		1
 
 CFLAGS+=	-I${.OBJDIR} -I${.CURDIR} \
@@ -120,11 +124,4 @@ dt_names.c:
 
 beforedepend:	dt_errtags.c dt_names.c
 
-beforeinstall:
-.if !defined(LIBRARIES_ONLY) && exists(${DESTDIR}/usr/lib/dtrace)
-.for file in ${DSRCS}
-	${INSTALL} -o ${BINOWN} -g ${BINGRP} -m ${NOBINMODE} ${.CURDIR}/${file} ${DESTDIR}/usr/lib/dtrace
-.endfor
-.endif
-
 .include <bsd.lib.mk>