Meta/Make: clean "version" file

Make

@@ -64,7 +64,9 @@ do
 	shift
 done
 
-$GIT describe --abbrev=4 HEAD | sed -e 's/-/./g' >version
+sh -c 'git describe --abbrev=4 HEAD' >/dev/null 2>&1 || {
+	$GIT describe --abbrev=4 HEAD | sed -e 's/-/./g' >version
+}
 
 make $d \
      GITWEB_CONFIG=$G \
@@ -72,3 +74,5 @@ make $d \
      ETC_GITCONFIG=$d/etc/gitconfig \
      CFLAGS="$O -Wall -Wdeclaration-after-statement -g" \
      "$@"
+
+rm -f version