fix keyboard input on OS X < 10.6

Since commit e4dc93f5, LibreOffice just beeps on any key press:
it's impossible to add symbols by using keyboard. This patch
fixes that.

conditionally reverts e4dc93f5d8d0df50f1a8b4594220d0c57703e03d

Change-ID: Id30e30775c0d0224954b8a1f05fd0d8d5f39cd4e
Reviewed-on: https://gerrit.libreoffice.org/9793
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>