guix: m2-planet: Update to 1.7.0.

* guix/git/mes.scm (m2-planet)[source]: Update to 1.7.0.
(native-inputs): Remove gcc-toolchain-7.
[arguments]: Add CC to make-flags.  Update sha256sum patch.

guix/git/mes.scm

@@ -90,37 +90,41 @@ get_machine.")
     (license gpl3+)))
 
 (define-public m2-planet
-  (let ((commit "1fc2aeab483208bd2ba117b21df3894c182470ec")
-        (revision "0"))
   (package
     (name "m2-planet")
-      (version (string-append "1.4.0-" revision "." (string-take commit 7)))
-      (source (origin
+    (version "1.7.0")
+    (source
+     (origin
        (method git-fetch)
        (uri (git-reference
              (url "https://github.com/oriansj/m2-planet.git")
-                      (commit commit)))
-                (file-name (git-file-name name version))
+             (commit (string-append "Release_" version))))
+       (file-name (string-append name "-" version ".tar.gz"))
        (sha256
         (base32
-                  "1fj3xiqcibdfi78b43nn6w8hs3vkz32yb06n8r5mna8pnjdmn00l"))))
+         "052j63xv44zqy7jndjw36jpyciz00p11d78w2rhy539qa5vdzad7"))))
     (native-inputs
-       `(("gcc-toolchain" ,gcc-toolchain-7)
-         ("mescc-tools" ,mescc-tools)))
+     `(("mescc-tools" ,mescc-tools)))
     (build-system gnu-build-system)
     (arguments
-       `(#:make-flags (list (string-append "PREFIX=" (assoc-ref %outputs "out")))
+     `(#:make-flags (list (string-append "PREFIX=" (assoc-ref %outputs "out"))
+                          (string-append "CC=" ,(cc-for-target)))
        #:tests? #f
        #:phases (modify-phases %standard-phases
                   (delete 'bootstrap)
-                    (delete 'configure))))
+                  (delete 'configure)
+                  (add-after 'unpack 'patch-prefix
+                    (lambda _
+                      (substitute* "sha256.sh"
+                        (("\\$\\(which sha256sum\\)") (which "sha256sum")))
+                      #t)))))
     (synopsis "The PLAtform NEutral Transpiler")
     (description
      "M2-Planet, The PLAtform NEutral Transpiler, when combined with
 mescc-tools compiles a subset of the C language into working binaries
 with introspective steps inbetween.")
     (home-page "https://savannah.nongnu.org/projects/mescc-tools")
-      (license gpl3+))))
+    (license gpl3+)))
 
 (define-public nyacc-0.99
   (package