[Mtools] compiling 4.0.0 on Solaris 9

[Zube]

Compiling 4.0.0 on Solaris 9 sparc initially fails because Solaris 9's
wchar.h does not contain some of the functions needed, such as wcsdup().
Commenting out the HAVE_WCHAR_H and HAVE_WCTYPE_H bits in config.h gets
me almost there.  However, charsetConv.c uses wcsnlen() and the obvious
define of:

define wcsnlen strnlen

does not work because strnlen() is not defined in Solaris 9.

Cheers,
Zube