Update license for RT-Thread kernel.

Add cconfig.h file for different version of GCC, which is automatically
detected and generated by scons script.

- missing free old memory after malloc new
- free memory when new size is zero

没用使用RT_USING_HEAP宏时，components.c文件第211行会报警告，增加一条语句用于消除此警告（使用四个空格代替TAB）

Fox example for the below example code:

#include <stdio.h>

void goodBye(void)
{
	printf("Good Bye!\n");
}

int main(int argc, char* argv[])
{
	printf("Hello World!\n");
	goodBye();
	return 0;
}