Some work on the Slirp TFTP server
- copied some defines from osdep.h to fix compilation on all Windows build systems
- ported TFTP option handling from the Bochs 'vnet' TFTP server


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12262 6c8e4198-a580-4521-a02f-c9ae86df1db9