git-gui: Correct size of dictionary name widget in options dialog

We don't need to fill this entire horizontal cavity, it looks really
bad on some platforms to stretch the widget out to fill the window.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
diff --git a/lib/option.tcl b/lib/option.tcl
index 3bfa2ed..ea80df0 100644
--- a/lib/option.tcl
+++ b/lib/option.tcl
@@ -193,9 +193,7 @@
 			${f}_config_new(gui.spellingdictionary) \
 			$all_dicts
 		pack $w.$f.$optid.l -side left -anchor w -fill x
-		pack $w.$f.$optid.v -side left -anchor w \
-			-fill x -expand 1 \
-			-padx 5
+		pack $w.$f.$optid.v -side right -anchor e -padx 5
 		pack $w.$f.$optid -side top -anchor w -fill x
 	}
 	unset all_dicts