WITH_META_MODE: Disable cookie handling for include installation.

Using a cookie with meta mode causes it to *not rerun* (as normal make
does) unless the command changes or filemon-detected files change.

After all of the work done here it turns out that skipping installation
is dangerous since the install commands use <dir>/*.h.  The actual build
command is not changing but the files installed are changing by the mere
act of adding a new header into the source tree.  Thus we cannot safely
use meta mode logic here.  It must always rerun and install the headers.
The install -C flag at least prevents churning timestamps when
installing a header that was already present.

Sponsored by:	EMC / Isilon Storage Division

include/Makefile

@@ -130,7 +130,7 @@ _MARCHS=	${MACHINE_CPUARCH}
 _MARCHS+=	x86
 .endif
 
-META_TARGETS+=	compat copies symlinks
+META_TARGETS+=	compat
 stage_includes: ${SHARED}
 
 # Take care of stale directory-level symlinks.
@@ -144,7 +144,7 @@ compat:
 	    -f ${.CURDIR}/../etc/mtree/BSD.include.dist \
 	    -p ${DESTDIR}${INCLUDEDIR} > /dev/null
 
-copies:
+copies: .PHONY .META
 .for i in ${LDIRS} ${LSUBDIRS} ${LSUBSUBDIRS} crypto machine machine/pc \
 	${_MARCHS}
 	if [ -d ${DESTDIR}${INCLUDEDIR}/$i ]; then \
@@ -230,7 +230,7 @@ copies:
 	${INSTALL} -C ${TAG_ARGS} -o ${BINOWN} -g ${BINGRP} -m 444 teken.h \
 	    ${DESTDIR}${INCLUDEDIR}/teken
 
-symlinks:
+symlinks: .PHONY .META
 	@${ECHO} "Setting up symlinks to kernel source tree..."
 .for i in ${LDIRS}
 	cd ${.CURDIR}/../sys/$i; \