Do not call into NETWinInfo in AbstractClient::setSkipPager

Summary:
There's a call to a virtual doSetSkipPager for performing this call and
Client implements it with the code which now is removed.

This fixes a crash when using setSkipPager for a Wayland window.

Test Plan:
Crash which happens with a new test case (see dependent phab
request) is fixed.

Reviewers: #kwin, #plasma

Subscribers: plasma-devel, kwin

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D9865

abstract_client.cpp

@@ -153,7 +153,6 @@ void AbstractClient::setSkipPager(bool b)
         return;
     m_skipPager = b;
     doSetSkipPager();
-    info->setState(b ? NET::SkipPager : NET::States(0), NET::SkipPager);
     updateWindowRules(Rules::SkipPager);
     emit skipPagerChanged();
 }