gnu: rust-dlib: Add 0.5.0.

* gnu/packages/crates-io.scm (rust-dlib-0.5): New variable.
(rust-dlib-0.4): Inherit from it.

gnu/packages/crates-io.scm

@@ -18420,8 +18420,33 @@ (define-public rust-dissimilar-1
 Google's diff-match-patch.")
     (license (list license:expat license:asl2.0))))
 
+(define-public rust-dlib-0.5
+  (package
+    (name "rust-dlib")
+    (version "0.5.0")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (crate-uri "dlib" version))
+       (file-name (string-append name "-" version ".tar.gz"))
+       (sha256
+        (base32
+         "1547hy7nrhkrb2i09va244c0h8mr845ccbs2d2mc414c68bpa6xc"))))
+    (build-system cargo-build-system)
+    (arguments
+     `(#:tests? #f                      ;FIXME: Several macros are not found.
+       #:cargo-inputs
+       (("rust-libloading" ,rust-libloading-0.7))))
+    (home-page "https://github.com/vberger/dlib")
+    (synopsis "Helper macros for manually loading optional system libraries")
+    (description
+     "This package provides helper macros for handling manually loading optional
+system libraries.")
+    (license license:expat)))
+
 (define-public rust-dlib-0.4
   (package
+    (inherit rust-dlib-0.5)
     (name "rust-dlib")
     (version "0.4.2")
     (source
@@ -18433,18 +18458,11 @@ (define-public rust-dlib-0.4
        (sha256
         (base32
          "0xlsf3lrz9hd7q3ff6lp5mw4kn3nbryn746kd07i93r6wg8ia7xi"))))
-    (build-system cargo-build-system)
     (arguments
      `(#:cargo-inputs
        (("rust-libloading" ,rust-libloading-0.6))))
     (inputs
-     (list rust-libloading-0.6))
-    (home-page "https://github.com/vberger/dlib")
-    (synopsis "Helper macros for manually loading optional system libraries")
-    (description
-     "This package provides helper macros for handling manually loading optional
-system libraries.")
-    (license license:expat)))
+     (list rust-libloading-0.6))))
 
 (define-public rust-dlv-list-0.2
   (package