Use raiseWindow also for confirm dialogs

    This should fix the case that the dialog opened
    in the foreground but a warning / confirm dialog
    opened in the background.

    * qt4/pinentryconfirm.cpp, qt4/pinentryconfirm.h (showEvent):
    New overwrite base class method to call raiseWindow.
    * NEWS: Mention this.
Add fallbacks for SetForegroundWindow

    If that foreground window fails pinentry-qt now tries to
    attach to the current foreground process and then tries
    to set the foreground window again. If that fails it also
    calls ShowWindow as a last resort.

    * qt4/pinentrydialog.cpp (raiseWindow): Add fallbacks in
    case SetForegroundWindow fails.
Check for MOC also if pinentry-qt is disabled

  * configure.ac: Call QT_PATH_MOC if pinentry_qt4 is not no.

--
  Previously the MOC lookup from m4/qt.m4 would only be called
  if pinentry-qt was at least maybe. The MOC variable defined by
  this macro is also used in pinentry-qt4 though.