Use the libreadline in Winedbg, if available

[Patrik Stridvall]

> at present, wine uses unconditionally a self supplied readline
> function. Appended patch tries to find out if libreadline is 
> available 
> and uses libreadline if available. I configured with and without
> libreadline and successfully compiled winedbg on my system.
> libreadline is a static library on my system and winedbg grew 90 kByte
> stripped and 110 kByte compiled with -g.

> Patrick: Can you check if my approach to recognize 
> libreadline is portable?

It looks like it is and it detects my self installed
libreadline on Solaris so I guess it is OK.

> (Resent patch: Original message dated 000910,
> rejected without notice or forgotten) 

A minor notice. Readline is GPL:ed (not LGPL:ed) which is not so good.
While it is without doubt legal for us to use and distribute,
it might cause trouble for other people.

However since you only link it with the debugger it is IMHO acceptable.
Alexandre might disagree though...