Create a separate script to generate osreldate.h rather than sourcing

newvers.sh into a temporary subshell with inline make rules.

Using a separate script fixes a variety of problems, including establishing
the correct dependencies in the makefiles.  It also eliminates a problem
with the way newvers.sh uses `realpath $0`, because $0 expands differently
within a script sourced into a rule in a makefile depending on the version
of make and of /bin/sh being used.  The latter can cause build breakage in a
cross-build environment, and can also make it difficult to compile 10.0 on
older pre-10.0 systems.

PR:		160646 174422
Submitted by:	Garrett Cooper <yaneurabeya@gmail.com>
Approved by:	re (gjb)
MFC after:	2 weeks

include/Makefile

@@ -104,19 +104,16 @@ SHARED?=	copies
 
 INCS+=	osreldate.h
 
-osreldate.h: ${.CURDIR}/../sys/conf/newvers.sh ${.CURDIR}/../sys/sys/param.h \
-    ${.CURDIR}/Makefile
-	@${ECHO} creating osreldate.h from newvers.sh
-	@MAKE=${MAKE}; \
-	PARAMFILE=${.CURDIR}/../sys/sys/param.h; \
-	. ${.CURDIR}/../sys/conf/newvers.sh; \
-	echo "$$COPYRIGHT" > osreldate.h; \
-	echo "#ifdef _KERNEL" >> osreldate.h; \
-	echo "#error \"<osreldate.h> cannot be used in the kernel, use <sys/param.h>\"" >> osreldate.h; \
-	echo "#else" >> osreldate.h; \
-	echo "#undef __FreeBSD_version" >> osreldate.h; \
-	echo "#define __FreeBSD_version $$RELDATE" >> osreldate.h; \
-	echo "#endif" >> osreldate.h
+NEWVERS_SH=		${.CURDIR}/../sys/conf/newvers.sh
+PARAM_H=		${.CURDIR}/../sys/sys/param.h
+MK_OSRELDATE_SH=	${.CURDIR}/mk-osreldate.sh
+
+osreldate.h vers.c: ${NEWVERS_SH} ${PARAM_H} ${MK_OSRELDATE_SH}
+	env ECHO="${ECHO}" \
+	    MAKE="${MAKE}" \
+	    NEWVERS_SH=${NEWVERS_SH} \
+	    PARAM_H=${PARAM_H} \
+	    ${MK_OSRELDATE_SH}
 
 .for i in ${LHDRS}
 INCSLINKS+=	sys/$i ${INCLUDEDIR}/$i

include/mk-osreldate.sh

@@ -0,0 +1,49 @@
+#!/bin/sh -
+# Copyright (c) 2013 Garrett Cooper
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+
+set -e
+
+CURDIR=$(pwd)
+ECHO=${ECHO:=echo}
+
+tmpfile=$(mktemp osreldate.XXXXXXXX)
+trap "rm -f $tmpfile" EXIT
+
+${ECHO} creating osreldate.h from newvers.sh
+
+export PARAMFILE="${PARAM_H:=$CURDIR/../sys/sys/param.h}"
+. "${NEWVERS_SH:=$CURDIR/../sys/conf/newvers.sh}"
+cat > $tmpfile <<EOF
+$COPYRIGHT
+#ifdef _KERNEL
+#error "<osreldate.h> cannot be used in the kernel, use <sys/param.h>"
+#else
+#undef __FreeBSD_version
+#define __FreeBSD_version $RELDATE
+#endif
+EOF
+mv $tmpfile osreldate.h