kernel: profile system when SYSTEM_PROFILER is defined.

* This enables a mechanism to profile almost the complete boot process
  (starting with main2()), if SYSTEM_PROFILER is defined to 1.
* You can access the profiling data using "profile -r".

build/config_headers/kernel_debug_config.h

@@ -133,5 +133,11 @@
 // Enables tracking of page allocations.
 #define VM_PAGE_ALLOCATION_TRACKING		0
 
+// Enables the (boot) system profiler for use with "profile -r"
+#define SYSTEM_PROFILER					0
+#define SYSTEM_PROFILE_SIZE				40 * 1024 * 1024
+#define SYSTEM_PROFILE_STACK_DEPTH		10
+#define SYSTEM_PROFILE_INTERVAL			10000
+
 
 #endif	// KERNEL_DEBUG_CONFIG_H