config(8): Fix broken ABI

r336019 introduced ${SRCTOP}/sys to the include paths in order to pull in a
new sys/{c,}nv.h. This is wrong, because the build tree's ABI isn't
guaranteed to match what's running on the host system.

Fix instead by removing -I${SRCTOP}/sys and installing the libnv headers
with `make -C lib/libnv includes`... this may or may not get re-worked in
the future so that a userland lib isn't installing includes from sys/.

Reported by:	bdrewery

lib/libnv/Makefile

@@ -17,6 +17,9 @@ SRCS+=	msgio.c
 SRCS+=	nvlist.c
 SRCS+=	nvpair.c
 
+INCSDIR=	${INCLUDEDIR}/sys
+INCS=	${SRCTOP}/sys/sys/cnv.h ${SRCTOP}/sys/sys/nv.h
+
 HAS_TESTS=
 SUBDIR.${MK_TESTS}+= tests
 

usr.sbin/config/Makefile

@@ -14,7 +14,7 @@ kernconf.c: kernconf.tmpl
 	${FILE2C} 'char kernconfstr[] = {' ',0};' < \
 	    ${SRCDIR}/kernconf.tmpl > kernconf.c
 
-CFLAGS+= -I. -I${SRCDIR} -I${SRCTOP}/sys
+CFLAGS+= -I. -I${SRCDIR}
 
 NO_WMISSING_VARIABLE_DECLARATIONS=