repo-add : don't change the modification time on depends and desc

The modification time on depends and desc file were changed to match the
modification time of the package file. I don't see why and we are actualling
losing information here. If we want to know the date of the package file, we
can just look inside the depends file. If we want to know when the entry was
created, we should not alter the modification time of depends and desc.

Besides, this had the non-obvious and undocumented side effect that the
depends file was always created, even if it was empty. And pacman actually
does require that. So I added a "touch depends" to always create the file.

Signed-off-by: Xavier Chantry <shiningxc@gmail.com>

scripts/repo-add.sh.in

@@ -262,6 +262,8 @@ db_write_entry()
 
 	# create depends entry
 	msg2 "$(gettext "Creating 'depends' db entry...")"
+	# create the file even if it will remain empty
+	touch "depends"
 	write_list_entry "DEPENDS" "$_depends" "depends"
 	write_list_entry "CONFLICTS" "$_conflicts" "depends"
 	write_list_entry "PROVIDES" "$_provides" "depends"
@@ -269,11 +271,6 @@ db_write_entry()
 
 	cd "$startdir"
 
-	# preserve the modification time
-	# Xav : what for?
-	pkgdir="$gstmpdir/$pkgname-$pkgver"
-	touch -r "$pkgfile" "$pkgdir/desc" "$pkgdir/depends"
-
 	return 0
 } # end db_write_entry