Misc fix

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

The digit in octal numbers should with in 0~7. Check on it in
token_proc_number. This issue is found by Clang.

Clang complains about "Null pointer argument in call to string
comparison function". So assert on it.

Fix some "unused variable" and "used before set" warnings.

Fix scons

Logtrace next

log_session_lvl is suitable for performance critical places where in
most cases, the log is turned off by level. If the session is const and
the level is greater than session->lvl, the whole function will be
optimized out.

Compiler may do more optimization when the parameter is const.

[USB]fix rt_usbd_set_config() BUG which set the USB device to configurat...

In SCons manual:

=================
In order to inform the C compiler about the repositories,  SCons will
add appropriate -I flags to the compilation commands for each directory
in the $CPPPATH list. So if we add the current directory to the
construction environment $CPPPATH like so:

    env = Environment(CPPPATH = ['.'])
    env.Program('hello.c')
    Repository('/usr/repository1')

Then re-executing SCons yields:

    % scons -Q
    cc -o hello.o -c -I. -I/usr/repository1 hello.c
    cc -o hello hello.o
=================

The additional include directory is definitely not what we want. Just
remove the additional Repository line.

BSPs could have their own components/ etc. If they point to the same
folder, SCons would find the wrong source code to compile.

update MSH ifconfig and add MSH netstat.

[shell] define FINSH_PROMPT as finsh_get_prompt when FINSH_USING_MSH enabled

When MSH enabled, the prompt will change at the two shells. So we should
use dynamic prompt when FINSH_USING_MSH defined.

Qemu realview vmm

When RT-Thread is running stand alone, it forgot to enable the
distributor of GIC.

This piece of code will enable the interrupt early before switching to
the first thread. Although it is harmless, but not prefect.

Qemu realview vmm

[USB]fix rt_usbd_set_config() BUG which set the USB device to configuration state before enumerating the device.

[vmm] add realview-pb-a8 VMM support

[msh] don't complain on empty command

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

Msh next

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.