KDE4: don't ignore write(2) return value

Silence the glibc compile warning and actually handle a wrong
return value.

Change-Id: Icdbc8e655d4b8ad20699dfd0abdbf3405a49f898
(cherry picked from commit e4a3bf06)
Reviewed-on: https://gerrit.libreoffice.org/18034Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>

vcl/unx/kde4/tst_exclude_socket_notifiers.hxx

@@ -74,7 +74,8 @@ static int tst_processEventsExcludeSocket()
     QSocketNotifier notifier( pipes[ 0 ], QSocketNotifier::Read );
     QObject::connect( &notifier, SIGNAL( activated( int )), &test, SLOT( slotReceived()));
     char dummy = 'a';
-    write( pipes[ 1 ], &dummy, 1 );
+    if( 1 != write( pipes[ 1 ], &dummy, 1 ) )
+        return 1;
     QEventLoop loop;
     loop.processEvents( QEventLoop::ExcludeSocketNotifiers );
     QVERIFY( !test.received );