Use libelf from base.

Index: cddl/usr.bin/ctfconvert/Makefile
--- cddl/usr.bin/ctfconvert/Makefile.orig
+++ cddl/usr.bin/ctfconvert/Makefile
@@ -35,8 +35,8 @@ CFLAGS+=	-I${.CURDIR}/../../../sys/cddl/compat/opensol
 		-I${OPENSOLARIS_USR_DISTDIR}/tools/ctf/common \
 		-I${OPENSOLARIS_USR_DISTDIR}/tools/ctf/cvt \
 		-I${OPENSOLARIS_SYS_DISTDIR}/uts/common \
-		-I/usr/local/include/elftoolchain
+		-I${LOCALBASE}/include/libdwarf
 
-LDADD=		-L/usr/local/lib/elftoolchain -ldwarf -lelf -lz -lpthread
+LDADD=		-L/usr/lib -L${LOCALBASE}/lib/ -ldwarf -lelf -lz -lpthread
 
 .include <bsd.prog.mk>