racket/gui: make list-box% columns more consistent across platforms

Cocoa: use ellipses instead of line wrapping
Gtk: allow column sizing below title width

Merge to v5.3.4
(cherry picked from commit 33700427f2)

collects/mred/private/wx/cocoa/list-box.rkt

@@ -21,6 +21,8 @@
 (import-class NSScrollView NSTableView NSTableColumn NSCell NSIndexSet)
 (import-protocol NSTableViewDataSource)
 
+(define NSLineBreakByTruncatingTail 4)
+
 (define-objc-class RacketTableView NSTableView
   #:mixins (FocusResponder KeyMouseResponder CursorDisplayer)
   [wxb]
@@ -30,6 +32,7 @@
          (let ([c (tell (tell NSCell alloc) initTextCell: #:type _NSString 
                         (if wx (send wx get-cell column row) "???"))]
                [font (and wx (send wx get-cell-font))])
+           (tellv c setLineBreakMode: #:type _NSUInteger NSLineBreakByTruncatingTail)
            (when font
              (tellv c setFont: font))
            c)

collects/mred/private/wx/gtk/list-box.rkt

@@ -162,6 +162,7 @@
              #f)])
       (when headers?
         (gtk_tree_view_column_set_resizable column #t)
+        (gtk_tree_view_column_set_min_width column 1)
         (when click-headers?
           (gtk_tree_view_column_set_clickable column #t))
         (when reorder-headers?