Makefile: add quick-install-doc for installing pre-built manpages

This adds and uses the install-doc-quick.sh file to
Documentation/, which is usable for people who track either the
'html' or 'man' heads in Junio's repository (prefixed with
'origin/' if cloned locally).  You may override this by
specifying DOC_REF in the make environment or in config.mak.

GZ may also be set in the environment (or config.mak) if you
wish to gzip the documentation after installing it.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/Makefile

@@ -32,6 +32,7 @@ man7dir=$(mandir)/man7
 # DESTDIR=
 
 INSTALL?=install
+DOC_REF = origin/man
 
 -include ../config.mak.autogen
 
@@ -112,3 +113,6 @@ $(patsubst %.txt,%.html,$(wildcard howto/*.txt)): %.html : %.txt
 
 install-webdoc : html
 	sh ./install-webdoc.sh $(WEBDOC_DEST)
+
+quick-install:
+	sh ./install-doc-quick.sh $(DOC_REF) $(mandir)

Documentation/install-doc-quick.sh

@@ -0,0 +1,31 @@
+#!/bin/sh
+# This requires a branch named in $head
+# (usually 'man' or 'html', provided by the git.git repository)
+set -e
+head="$1"
+mandir="$2"
+SUBDIRECTORY_OK=t
+USAGE='<refname> <target directory>'
+. git-sh-setup
+export GIT_DIR
+
+test -z "$mandir" && usage
+if ! git-rev-parse --verify "$head^0" >/dev/null; then
+	echo >&2 "head: $head does not exist in the current repository"
+	usage
+fi
+
+GIT_INDEX_FILE=`pwd`/.quick-doc.index
+export GIT_INDEX_FILE
+rm -f "$GIT_INDEX_FILE"
+git-read-tree $head
+git-checkout-index -a -f --prefix="$mandir"/
+
+if test -n "$GZ"; then
+	cd "$mandir"
+	for i in `git-ls-tree -r --name-only $head`
+	do
+		gzip < $i > $i.gz && rm $i
+	done
+fi
+rm -f "$GIT_INDEX_FILE"

Makefile

@@ -824,6 +824,8 @@ install: all
 install-doc:
 	$(MAKE) -C Documentation install
 
+quick-install-doc:
+	$(MAKE) -C Documentation quick-install