gitk: Add emacs editor variable block

Help contributors use the correct indentation style.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/gitk b/gitk
index ba91bba..9da0526 100755
--- a/gitk
+++ b/gitk
@@ -11610,3 +11610,9 @@
 }
 
 getcommits {}
+
+# Local variables:
+# mode: tcl
+# indent-tabs-mode: t
+# tab-width: 8
+# End: