Move obscure lib/ installation of /usr/lib/include symlink to include/.

This avoids the need for an afterinstall: hook and a check for LIBRARIES_ONLY.
It also now respects INCLUDEDIR.

This came in r249484.

Sponsored by:	EMC / Isilon Storage Division

include/Makefile

@@ -104,6 +104,8 @@ NEWVERS_SH=		${SYSDIR}/conf/newvers.sh
 PARAM_H=		${SYSDIR}/sys/param.h
 MK_OSRELDATE_SH=	${.CURDIR}/mk-osreldate.sh
 
+SYMLINKS+= ${INCLUDEDIR} ${LIBDIR}/include
+
 osreldate.h: ${NEWVERS_SH} ${PARAM_H} ${MK_OSRELDATE_SH}
 	env NEWVERS_SH=${NEWVERS_SH} PARAMFILE=${PARAM_H} SYSDIR=${SYSDIR} \
 	    sh ${MK_OSRELDATE_SH}

lib/Makefile

@@ -314,11 +314,6 @@ _libusbhid=	libusbhid
 _libusb=	libusb
 .endif
 
-.if !defined(LIBRARIES_ONLY)
-afterinstall:
-	${INSTALL_SYMLINK} ../include ${DESTDIR}/usr/lib/include
-.endif
-
 .if !make(install)
 SUBDIR_PARALLEL=
 .endif