OS X: fix wxFileDialog::SetupExtraControls()'s sandbox test.

OS X 10.9 (possibly earlier) don't have nil contentView in NSSavePanel
anymore, a NSRemoteView instance is used. The wx code that follows this
test still crashes under sandbox, though, so update the check to use the
APP_SANDBOX_CONTAINER_ID environment variable, which is only set when
running under the sandbox.

This is just another quick fix for the existing uncomfortably long-lived
sandbox crash hotfix, not a proper solution.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@76208 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/cocoa/filedlg.mm

@@ -457,7 +457,7 @@ void wxFileDialog::SetupExtraControls(WXWindow nativeWindow)
     // for sandboxed app we cannot access the outer structures
     // this leads to problems with extra controls, so as a temporary
     // workaround for crashes we don't support those yet
-    if ( [panel contentView] == nil )
+    if ( [panel contentView] == nil || getenv("APP_SANDBOX_CONTAINER_ID") != NULL )
         return;
     
     wxNonOwnedWindow::Create( GetParent(), nativeWindow );