gnu: Add rust-gobject-sys-0.18.

* gnu/packages/crates-gtk.scm (rust-gobject-sys-0.18): New variable.
(rust-gobject-sys-0.17): Inherit from rust-gobject-sys-0.18.

Change-Id: Id5ba73cfa2071c712d4e6a3f8b5f464ce6ed243f
Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/crates-gtk.scm

@@ -1599,8 +1599,37 @@
        (("rust-shell-words" ,rust-shell-words-0.1)
         ("rust-tempfile" ,rust-tempfile-3))))))
 
+(define-public rust-gobject-sys-0.18
+  (package
+    (name "rust-gobject-sys")
+    (version "0.18.0")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (crate-uri "gobject-sys" version))
+       (file-name (string-append name "-" version ".tar.gz"))
+       (sha256
+        (base32 "0i6fhp3m6vs3wkzyc22rk2cqj68qvgddxmpaai34l72da5xi4l08"))))
+    (build-system cargo-build-system)
+    (arguments
+     `(#:tests? #f ; `G_TYPE_FUNDAMENTAL_MAX` constant mismatch with gcc
+       #:cargo-inputs
+       (("rust-glib-sys" ,rust-glib-sys-0.18)
+        ("rust-libc" ,rust-libc-0.2)
+        ("rust-system-deps" ,rust-system-deps-6))
+       #:cargo-development-inputs
+       (("rust-shell-words" ,rust-shell-words-1)
+        ("rust-tempfile" ,rust-tempfile-3))))
+    (native-inputs (list pkg-config))
+    (inputs (list glib))
+    (home-page "https://gtk-rs.org/")
+    (synopsis "FFI bindings to libgobject-2.0")
+    (description "This package provides FFI bindings to libgobject-2.0.")
+    (license license:expat)))
+
 (define-public rust-gobject-sys-0.17
   (package
+    (inherit rust-gobject-sys-0.18)
     (name "rust-gobject-sys")
     (version "0.17.10")
     (source (origin
@@ -1610,7 +1639,6 @@
               (sha256
                (base32
                 "0ql0pcab6dxjapiglxcjaavbbh1sznyc2wj5q273b9j0fwqw6d6d"))))
-    (build-system cargo-build-system)
     (arguments
      `(;; XXX: Tests are sensitive to the version of glib, even though
        ;; the library supports a wide range.  Skip for now.
@@ -1621,15 +1649,7 @@
         ("rust-system-deps" ,rust-system-deps-6))
        #:cargo-development-inputs
        (("rust-shell-words" ,rust-shell-words-1)
-        ("rust-tempfile" ,rust-tempfile-3))))
+        ("rust-tempfile" ,rust-tempfile-3))))))
-    (native-inputs
-     (list pkg-config))
-    (inputs
-     (list glib))
-    (home-page "https://gtk-rs.org/")
-    (synopsis "FFI bindings to libgobject-2.0")
-    (description "This package provides FFI bindings to libgobject-2.0.")
-    (license license:expat)))
 
 (define-public rust-gobject-sys-0.15
   (package