Fix compile warning: variable "c" was declared but never referenced, when RT_USING_CONSOLE is disable.

Add mdk5 building

efm32: return empty variable instead of Return('')

SCons: allow set object files in DefineGroup

The source files can be the raw file names end with .c or .o. So return
the raw file names is more flexible than wrap them with Object.

update RW009 driver: add softAP support.

add a support for rx62n

update the change logs

modified the comments of block device geometry structure, to tell everyone the unit of block_size is byte.

bsp:fix the bug of lpc43xx uart interrupt enable in driver initialize.

romfs: fix a use-before-set bug on checking the dirent

[BSP] Add GCC compiler support for mb9bf568r

ymodem: fix examples due to new API

Romfs next

System will crash when the romfs is erased. Add checks before using them
to avoid it.

[CME_M7] add GCC compile support.

[BSP] fix GCC compiling issue in LPC408x bsp

romfs: declare the dummy entry as weak