Serial mouse detection fixes (required for CTMOUSE.EXE)
- added support for 16 bit access to serial port registers
- fixed entering mouse detection mode with DTR/RTS
- report serial port mode in log file


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11719 6c8e4198-a580-4521-a02f-c9ae86df1db9