This commit makes the function only call client_ignore_enterleave_events() when
it actually has to. Since we expect that most of the time, no client's geometry
is changed, this means that most of the time this function is not called.
Fixes: https://github.com/awesomeWM/awesome/issues/1107
Signed-off-by: Uli Schlachter <psychon@znc.in>