[StGIT PATCH not for master] Use gitk --argscmd in contrib/stg-gitk.

This allows to ask gitk to recompute the list of patches to show at
every refresh.  Before this, we had problems with 'stg-gitk --all':

 - deleting a patch that was existing at startup time would trigger an
 "unknown ref" error from gitk and force to quit/restart manually;
 - patches created since startup were only visible when applied, or
 when below one of the startup patches.

Signed-off-by: Yann Dirson <redacted>
---

Note that this flag is added by the gitk patch I just posted, so it
should not be applied to StGIT master right now - we want that git
gets released with the necessary support before we do that.

 contrib/stg-gitk |   26 ++++++++++++++++++++------
 1 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/contrib/stg-gitk b/contrib/stg-gitk
index dd01ef0..f2fca84 100755
--- a/contrib/stg-gitk
+++ b/contrib/stg-gitk

@@ -20,11 +20,16 @@ usage()
 }
 
 allbranches=0
-case "$1" in
---all) allbranches=1; shift ;;
---*) usage ;;
-*) break ;;
-esac
+refsonly=0
+while [ "$#" -gt 0 ]; do
+    case "$1" in
+	--refs) refsonly=1 ;;
+	--all) allbranches=1 ;;
+	--*) usage ;;
+	*) break ;;
+    esac
+    shift
+done
 
 if [ $allbranches = 1 ] && [ "$#" -gt 0 ]; then
     usage

@@ -58,4 +63,13 @@ else
     done
 fi
 
-gitk $(find $refdirs -type f -not -name '*.log' | cut -c${GIT_DIR_SPKIPLEN}- )
+printrefs()
+{
+    find $refdirs -type f -not -name '*.log' | cut -c${GIT_DIR_SPKIPLEN}-
+}
+
+if [ $refsonly = 1 ]; then
+    printrefs
+else
+    gitk --argscmd="$0 --refs $@"
+fi