new HAVE_XXX macro for acinclude.m4

[Richard]

I'm trying to add a test for a Qt feature to acinclude.m4, and inserted 
the following text at line 456:

dnl
dnl Check whether the Qt QTabWidget::setMovable() function exists.
dnl This function was added in Qt 4.5.
dnl
AC_DEFUN([OCTAVE_CHECK_FUNC_QTABWIDGET_SETMOVABLE], [
  AC_CACHE_CHECK([whether Qt has the QTabWidget::setMovable() function],
    [octave_cv_func_qtabwidget_setmovable],
    [AC_LANG_PUSH(C++)
    ac_octave_save_CPPFLAGS="$CPPFLAGS"
    CPPFLAGS="$QT_CPPFLAGS $CPPFLAGS"
    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
        #include <QTabWidget>
        class tab_widget : public QTabWidget
        {
        public:
          tab_widget (QObject *parent = 0) : QTabWidget (parent) { 
this->setMovable (true); }
          ~tab_widget () {}
        };
        ]], [[
        tab_widget tw;
        ]])],
      octave_cv_func_qtabwidget_setmovable=yes,
      octave_cv_func_qtabwidget_setmovable=no)
    CPPFLAGS="$ac_octave_save_CPPFLAGS"
    AC_LANG_POP(C++)
  ])
  if test $octave_cv_func_qtabwidget_setmovable = yes; then
    AC_DEFINE(HAVE_QTABWIDGET_SETMOVABLE, 1,
      [Define to 1 if Qt has the QTabWidget::setMovable() function.])
  fi
])


However, this is completely ignored by configure as far as I can tell. 
I'm building out-of-tree and I did ./bootstrap ; cd build ; configure. 
Am I missing some step here? Or is there some mistake in the macro I 
don't see?

Thanks
Richard

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