VC++ build repair

[nando]

With the few appended changes, GNU Go builds cleanly with VC++.

[nando]

READLINE is always 'defined', and sometimes (with VC++ for instance) it is set to 0

[arend]

This will cause warnings on other platforms, since by default READLINE is just undefined. We have to fix this one way (not defining READLINE for VC++) or another (defining READLINE to 0 by default, which would be the normal GNU Go practice).

[arend]

#define READLINE to 0 instead of leaving it undefined

[arend]

I suggest to use the attached readline_configure_7.8.1.diff in addition to nando_7_8.3.diff.