[Minor] Simplify creation of dist tarball that is reproducible

Instead of archiving files from the working tree, distribute files as
committed. Use the 'git archive' command to achieve this, it results in
a reproducible tarball with the same timestamp as the latest commit.

dist.sh

@@ -1,5 +1,8 @@
 #!/bin/sh
+# Creates a tarball with the concatenation of a git tree and the submodules.
+# Hidden files such as .gitignore are skipped.
 
+# GNU tar
 TAR=${2:-"tar"}
 
 if [ $# -lt 1 ] ; then
@@ -10,24 +13,17 @@ fi
 FNAME=$1
 PREFIX=`basename $FNAME | sed -e 's/\.tar.*$//'`
 
-OUT=""
-while true ; do
-	_mktemp=`which mktemp`
-	if [ F"$_mktemp" != "F" ] ; then
-		OUT=`$_mktemp /tmp/files-XXXXXXXX`
-		break
-	else
-		OUT="/tmp/files-`strings -7 /dev/urandom | head -1 | sed -e 's/[^[:alnum:]]//g'`"
-	fi
-	if [ ! -f "$OUT" ] ; then break ; fi
-done
+ALL_TAR=$(mktemp) || { echo "mktemp is missing!"; exit 1; }
+TMP_TAR=$(mktemp) || { echo "mktemp is missing!"; exit 1; }
+trap 'rm -f "$TMP_TAR" "$ALL_TAR"' EXIT
 
-git ls-files > $OUT
-SUBMODULES=`git submodule | cut -d ' ' -f 3`
+# Create tarball for main repo contents.
+git archive --prefix="$PREFIX/" HEAD ":!.*" ":!**/.*" > "$ALL_TAR"
 
-for sub in $SUBMODULES ; do
-	(cd $sub && git ls-files | sed -e "s|^|$sub/|" >> $OUT)
-done
+# Append submodule contents, if any.
+export PREFIX TMP_TAR ALL_TAR
+git submodule --quiet foreach --recursive \
+	'git archive --prefix="$PREFIX/$displaypath/" HEAD ":!.*" ":!**/.*" > "$TMP_TAR";
+	 tar Af "$ALL_TAR" "$TMP_TAR"'
 
-${TAR} -c --exclude='.[^/]*' --exclude='*.xz' --exclude='*.gz' --no-recursion --transform "s|^|$PREFIX/|" -a -T $OUT -v -f $FNAME
-rm -f $OUT
+xz < "$ALL_TAR" > "$FNAME"