reverted a change to have an assert instead of a g_return_val_if_fail()

reverted a change to have an assert instead of a g_return_val_if_fail()

Mon Oct  2 15:50:16 2006  Tim Janik  <timj@gtk.org>

        * gvalue.c (g_value_peek_pointer): reverted a change to have an
        assert instead of a g_return_val_if_fail() here. libraries (and
        programs) should only ever g_assert or g_error if there is no way
        to carry on with the current program state. that's clearly not
        the case here.

        * ChangeLog: added missing changelog entry for 2003-12-30.