Remove obsolete entries:

Remove obsolete entries:
 - 'Why is gcc failing'
 - 'Why can't bison find bison.simple or bison.hairy?'
Remove disclaimer from up-to-date entries (possibly with some minor changes):
 - 'How is fork() implemented?'
 - 'How do symbolic links work?'
 - 'How do I compile a Win32 executable that doesn't use Cygwin?'
 - 'How do I make the console window go away?'
 - 'Why does make complain about a "missing separator"?'
 - 'Why can't we redistribute Microsoft's Win32 headers?'
 - 'How can I debug what's going on?'
 - 'Can I use a system trace mechanism instead?'
 - 'Can I use the gdb debugger to debug programs built by VC++?'
 - 'Where can I find info on x86 assembly?'
 - 'Why not use DJGPP?'