Make shared data access thread-safe
- use LibVNCServer macros for pthread mutex support in the keyboard / mouse code
- workaround for WIN32: use critical section stuff instead (not yet present in
  LibVNCServer)


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11710 6c8e4198-a580-4521-a02f-c9ae86df1db9