* [kernel][mem] Multiple instances of small memory allocation algorithm

* [kernel][mem] Change small memory management algorithm memory header flag

* [kernel][mem] Fix assertion problem

* [kernel][slab] Multiple instances of slab memory management algorithm

* [kernel][memheap] Remove rt_malloc/rt_free/rt_realloc and other related memory interfaces

* [kernel][mem] Clean up memory space of small memory management objects

* [kernel][kservice] Add memory application interface and thread protection interface

* [kernel][kservice] Fix function return value problem

* [kernel][memheap] Optimize memheaptrace print

* [kernel][memheap] Support best mode

* [kernel][memory] Remove semaphore lock

* [kernel][memheap] Add locked flag

* [kernel][memory] Support malloc memory in interrupt

* [kernel][memheap] Add 'memheapcheck' cmd

* [kernel][mem] Fix failure to request full memory

* [kernel][memheap] Fix compilation warning

* [kernel][mem] Fix mem realloc ASSERT

* [examples][testcases] Add small mem testcase

* [examples][mem_tc] Modify test memory size

* [examples][testcases] Add slab memory management algorithm test case

* [examples][testcases] fix small memory management algorithm test case

* [kernel][memory] Adjusting memory allocation algorithm object definition and interface

* [kernel][memory] Fix compilation warning

* [examples][utest] Fix mem test case

* [examples][utest] fix slab test case

* [utest][testcases] Shorten test time

* [kernel][memory] Formatting code

* [examples][utest] Adjust test run time

* [examples][utest] Formatting code

* [bsp] update all rtconfig.h

Signed-off-by: chenyong <1521761801@qq.com>

The ptr is set in the following code. So remove the first one.

Just branch out and no complain on command length == 0;

When DFS_USING_WORKDIR is enabled, msh will try to chdir if the command
is not found. For example, if there is folder named "SD", and there is
no `SD` command and `SD.mo` module, typing "SD" in msh will cd to the
folder.

In more detail, the execution order right now is:

1. built-in command
2. module
3. cd to path

If you have a folder named "ps", you have to run `cd ps` to change the
working dir.

Msh can execute module directly. So try to auto-complete the path when
user press TAB. There is a chance that the path is a module.

fix msh_exec(char* cmd, rt_size_t length) bug