bogus version check after guile 2.0 release

[Matei Conovici]

In guile/g-wrap/guile-compatibility.h there's this version check which
enables some compat features.

/* Define this macro if Guile 1.7.x or better is in use. */
#if defined (SCM_MINOR_VERSION) && (SCM_MINOR_VERSION >= 7) && \
    defined (SCM_MAJOR_VERSION) && (SCM_MAJOR_VERSION >= 1)
#define SCM_VERSION_17X 1
endif

It became bogus after guile 2.0 release, as SCM_MINOR_VERSION is now 0
or 1.

With this taken care of, g-wrap (and guile-gnome-platform) compile
cleanly with the new guile.

Matei