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;
}

rename _errno to __rt_errno for conflict in WIN32.

1. Change the type of RT_DEBUG_THREAD to int;
2. Add Kconfig of VBUS.

1. Add macro check in rtdebug.h;
2. Use RT_USING_POSIX for poll/select, stdin etc.
3. Split dfs_posix.h to dfs_posix.h, dfs_poll.h and dfs_select.h;

1. Add signal implementation;
2. Change the 'rt_uint8_t' of cmd to 'int';

和一些使用这个宏的components起了冲突，无法编译通过。

1. upddate kernel module to support i386
2. update libdl to support open *.so by absolute path
3. new test case bsp/x86/src/hello.c to test i386 module feature
Signed-off-by: Nparai <parai@foxmail.com>

modify：     ../../libcpu/risc-v/e310/stack.c
	rmove unused macro definition
modify：     ../../src/idle.c
	Return to the original version