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>

lib/option.tcl

@@ -193,9 +193,7 @@ proc do_options {} {
 			${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