[colormanager] Fix build on older glib

Summary:
Copies the approach we do for various GL calls not existing on the
system headers.

See D25962

Reviewers: #kwin, romangg

Reviewed By: #kwin, romangg

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D26553

colorcorrection/clockskewnotifierengine_linux.cpp

@@ -24,6 +24,10 @@
 #include <sys/timerfd.h>
 #include <unistd.h>
 
+#ifndef TFD_TIMER_CANCEL_ON_SET // only available in newer glib
+#define TFD_TIMER_CANCEL_ON_SET (1 << 1)
+#endif
+
 namespace KWin
 {