Add a todo for a new timing API implementation that would work for Linux systems

as of kernel 2.6.25 and glibc 2.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@152990 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/timing.h

@@ -43,6 +43,9 @@
   4) Multiple 'event types', so that the code using the timer can
      know whether the wakeup it received was due to a periodic trigger
      or a continuous trigger.
+
+  \todo Create an implementation of this API for Linux based on the
+   following API: http://www.kernel.org/doc/man-pages/online/pages/man2/timerfd_create.2.html
  */
 
 #ifndef _ASTERISK_TIMING_H