Removed two unused macros in iostats_context

Summary: Removed two unused macros in iostats_context

Test Plan: make all check

Reviewers: sdong, rven, IslamAbdelRahman, kradhakrishnan, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40005

util/iostats_context_imp.h

@@ -34,13 +34,6 @@
 #define IOSTATS(metric)                        \
   (iostats_context.metric)
 
-// Stop the timer and update the metric
-#define IOSTATS_TIMER_STOP(metric)          \
-  iostats_step_timer_ ## metric.Stop();
-
-#define IOSTATS_TIMER_START(metric)          \
-  iostats_step_timer_ ## metric.Start();
-
 // Declare and set start time of the timer
 #define IOSTATS_TIMER_GUARD(metric)                                       \
   PerfStepTimer iostats_step_timer_ ## metric(&(iostats_context.metric));  \
@@ -57,7 +50,5 @@
 #define IOSTATS(metric) 0
 
 #define IOSTATS_TIMER_GUARD(metric)
-#define IOSTATS_TIMER_STOP(metric)
-#define IOSTATS_TIMER_START(metric)
 
 #endif  // IOS_CROSS_COMPILE