tools: add an option to generate cscope database

When --cscope option is given to Scons, it will generate a cscope
cross-reference database in current directory, which is useful in
Vim(and other cscope-aware text editors). For example, `scons -s
--cscope` will do nothing except generating the database. You can use
this option with other options together.

It is inspired by the `make cscope` of Linux.

Rm48x50

format s3c24x0 serial.c and mini2440 rtconfig.py

format the s3c24x0 serial.c and mini2440 rtconfig.py

完善生成codeblock工程功能。

indent format cortex-m3/cpuport.c, thank peter.uboot@gmail.com

Signed-off-by: Nvisitor83 <root@wolflouis.(none)>

udisk can be ejected

usb: add USB_MSG_PLUG_OUT event

Some driver will emit USB_MSG_DATA_NOTIFY before the USB get configured.
Filter out those events.

When the core received an USB_MSG_PLUG_OUT event, it will stop all the
classes. This make a chance that the classes could get rid off doing
useless stuff while the USB cable is plugged out.

Rm48x50 updates

Rm48x50

You need to turn on RT_VFP_LAZY_STACKING in rtconfig.h. By default, RTT
will turn on VFP for all threads and stack all the VFP registers. When
doing lazy stacking, VFP will only be turned on for the thread who
issued VFP instructions.

Currently, if a thread turned on VFP, it cannot be turned off. RTT will
never know what time the thread doesn't need VFP any more. The thread
might could turn off the VFP for it self in proper time.

VFP instructions only have IA(Increment After)/DB(Decrement Before)
mode. To keep consistency, just change STM/LDM to DB/IA accordingly.

This support Common VFPv2 sub-architecture.

For pull request