bootstrap: work also when there are no .po files in po/

* bootstrap (update_po_files): Complete the change that I began
in 7ba2dd808232cff3ee76aaceb97f4381c3c9cde4.

diff --git a/bootstrap b/bootstrap
index 56bdbc8..6226973 100755 (executable)
--- a/bootstrap
+++ b/bootstrap
@@ -273,7 +273,7 @@ update_po_files() {
 
   langs=`cd $ref_po_dir && echo *.po|sed 's/\.po//g'`
   test "$langs" = '*' && langs=x
-  for po in `cd $ref_po_dir && echo *.po|sed 's/\.po//g'`; do
+  for po in $langs; do
     case $po in x) continue;; esac
     new_po="$ref_po_dir/$po.po"
     cksum_file="$ref_po_dir/$po.s1"