bug#16736: Compiling a Lisp file causes display to flash off and on

[martin rudalics]

> Bisected to:
>
>     revno: 115971
>     committer: martin rudalics <rudalics@gmx.at>
>     branch nick: trunk
>     timestamp: Sat 2014-01-11 10:31:09 +0100
>     message:
>       Fix handling of internal borders (Bug#16348).

Does anything change when you set the frame's internal border width to
zero?  Does anything change when you disable the calls to
x_clear_under_internal_border?  If so, can you spot one of these calls
as the offending one?  I'm yet too silly to understand what's going on
here.

Thanks, martin