Using Checked C version of FreeRTOS Kernel

With the help of 3C, we converted the FreeRTOS Kernel into Checked C. You can use this version of kernel in your project instead of the C version.

The code for converted version can be found here. The following steps assume you have Checked C version of clang in your system.

Compiling the kernel

Update the Makefile with the path to FreeRTOS folder. This is needed if projCOVERAGE_TEST is set to 0 since one of the trace header files have to be modified to work with our kernel. You can find this modified version here.
```
  FREERTOS_ROOT := /path/to/FreeRTOS
  FREERTOS_DIR := $(abspath $(FREERTOS_ROOT))/FreeRTOS
  FREERTOS_PLUS_DIR := $(abspath $(FREERTOS_ROOT))/FreeRTOS-Plus
```
Include the config file required for your application. The following folder contains the config file for the Posix_GCC demo application.
```
  INCLUDE_DIRS += -I$(FREERTOS_DIR)/Demo/Posix_GCC
```
Now you can compile the kernel with make.

Using the kernel

One thing to keep in mind is that your application should be compiled using the modified FreeRTOS.h. This means that the application have to be compiled using the Checked C version of clang.

Modify the Makefile of your application so that it stops after all the object files are created. You can also remove the kernel file compilation steps from the Makefile since we already have the Checked C version object files with us.

To get the final application, use the Checked C kernel object files during the final linking step. The following is the command for Posix_GCC demo application.

$ gcc code_coverage_additions.o console.o main_blinky.o main.o main_full.o run-time-stats-utils.o croutine.o event_groups.o list.o queue.o stream_buffer.o tasks.o timers.o heap_3.o wait_for_event.o port.o AbortDelay.o BlockQ.o blocktim.o countsem.o death.o dynamic.o EventGroupsDemo.o flop.o GenQTest.o integer.o IntSemTest.o MessageBufferAMP.o MessageBufferDemo.o PollQ.o QPeek.o QueueOverwrite.o QueueSet.o QueueSetPolling.o recmutex.o semtest.o StaticAllocation.o StreamBufferDemo.o StreamBufferInterrupt.o TaskNotify.o TimerDemo.o trcKernelPort.o trcSnapshotRecorder.o trcStreamingRecorder.o trcStreamingPort.o -ggdb3 -pthread -O3 -o build/posix_demo

Path to object files are emitted in the above command to make it more readable.