gitk: Use bindshiftfunctionkey to bind Shift-F5

Signed-off-by: Andrew Wong <andrew.kw.w@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/gitk b/gitk
index f8f89a5..d53fdb2 100755
--- a/gitk
+++ b/gitk
@@ -2501,7 +2501,7 @@
     bindkey ? {dofind -1 1}
     bindkey f nextfile
     bind . <F5> updatecommits
-    bind . <Shift-F5> reloadcommits
+    bindmodfunctionkey Shift 5 reloadcommits
     bind . <F2> showrefs
     bindmodfunctionkey Shift 4 {newview 0}
     bind . <F4> edit_or_newview