in rt_console_set_device, open new device first and get the new device to _console_device.
我在编写程序时，在device驱动中打印log，但是使用rt_kprintf时，如果_console_device存在非空，那就执行驱动的write函数，但是这是device还没有初始化成功，但是已经提前给_console_device赋值，导致了程序无故fault，以上述修改可避开这样的矛盾。

[Kernel]when the macro of RT_USING_COMPONENTS_INIT is not open ,then remove the source of components.c  from the project.
Signed-off-by: pangwei <271372443@qq.com>

Fix a regression on 62a0172d.

The old `--keep` parameter for Keil is wrong. RTFM of Keil and get it
right.

Fix a regression on 62a0172d.

The old `--keep` parameter for Keil is wrong. RTFM of Keil and get it
right.

This will ease the debugging of double-free bug.

Commit a6251a43 changed the serial device to check open_flag
instead of flag. So we should change the rt_kprintf counterpart as well.

ARMCC will define __GNUC__ in "GNU mode"(with --gnu command line
option). So iff __GNUC__ && !__CC_ARM is GCC.

Use signed int as array index is unsecure.

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.

relation=>relocation

When thread wake up from waiting for memory, there is a chance that
there is no memory available in high pressure. So use a loop to check
again. Otherwise, there will be a NULL reference.

[Kernel] The rt_object_find routine can support to find an object inside a module. The usage is: rt_object_find("module_name/object_name").