[GDB stub]add GDB stub

add CME-M7 support.

sync

[YModem] YModem optimization;
[BSP] Add more error handling in STM32F1 bsp. 

[bsp] Fix the spelling errors. 

drvers->drivers

update RW009 driver.

Remove unsupport syntex for python 2.6.

Dict Comprehensions is imported in Python 2.7 & 3.0 which is PEP 274 [1]. Some
OS like CentOS 6 which is use Python 2.6 cannot support this syntex.

[1] http://legacy.python.org/dev/peps/pep-0274/Signed-off-by: NXiongfei Guo <xfguo@credosemi.com>

kernel/idle: fix rt_thread_idle_excute in high optimization level

The rt_list_isempty has prototype of "int rt_list_isempty(const rt_list_t *l)".
So the compiler has a good reason that the rt_thread_defunct list does
not change within rt_thread_idle_excute thus optimize the "while" loop
into a "if".

So add the volatile qualifier when test against the rt_thread_defunc list.

[Serial] BUG Fix: data be send twice in mode that other than polling