ndp.c doesn't have any #ifdef INET6 preprocessor directive, I can't see how keeping that in CPPFLAGS changes anything. While here, -I${.CURDIR} isn't needed either. Verified with sha256(1).
ok? Index: Makefile =================================================================== RCS file: /cvs/src/usr.sbin/ndp/Makefile,v retrieving revision 1.3 diff -u -p -r1.3 Makefile --- Makefile 9 Aug 2013 17:52:12 -0000 1.3 +++ Makefile 2 May 2016 11:15:58 -0000 @@ -4,6 +4,4 @@ PROG= ndp SRCS= ndp.c gmt2local.c MAN= ndp.8 -CPPFLAGS+=-DINET6 -I${.CURDIR} - .include <bsd.prog.mk> -- jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE