guile-next package needs new native-search-paths

[Thompson, David]

Hey everyone,

First of all: Thanks, Ludo, for the new guile-next package.  I tried
building it myself but couldn't figure out how to make the test suite
pass.

There's just one small issue: The native search paths are wrong.  They
are using the 2.2 search paths currently and thus you can't use it
as-is to develop projects that depend on other Guile libraries. The
fix is just to add this to the package recipe:

(native-search-paths
     (list (search-path-specification
            (variable "GUILE_LOAD_PATH")
            (files '("share/guile/site/3.0")))
           (search-path-specification
            (variable "GUILE_LOAD_COMPILED_PATH")
            (files '("lib/guile/3.0/site-ccache"
                     "share/guile/site/3.0")))))

Any objection to me pushing a commit that does this to master?

- Dave