Add stats header file to mbed.h

All API header files should be part of mbed.h

Author: deepikabhavnani

mbed.h

@@ -92,6 +92,7 @@
 #include "platform/DirHandle.h"
 #include "platform/CriticalSectionLock.h"
 #include "platform/DeepSleepLock.h"
+#include "platform/mbed_stats.h"
 
 // mbed Non-hardware components
 #include "platform/Callback.h"

rtos/TARGET_CORTEX/mbed_rtx_conf.h

@@ -45,11 +45,7 @@
 #error "OS Tickrate must be 1000 for system timing"
 #endif
 
-#if !defined(OS_STACK_WATERMARK) && defined(MBED_STACK_STATS_ENABLED)
-#define OS_STACK_WATERMARK          1
-#endif
-
-#if !defined(OS_STACK_WATERMARK) && defined(MBED_ALL_STATS_ENABLED)
+#if !defined(OS_STACK_WATERMARK) && (defined(MBED_STACK_STATS_ENABLED) || defined(MBED_ALL_STATS_ENABLED))
 #define OS_STACK_WATERMARK          1
 #endif