gnu: xxhash: Update to 0.8.1.

* gnu/packages/digest.scm (xxhash): Update to 0.8.1.
[arguments]: Add a new 'fix-man-page-links phase.

gnu/packages/digest.scm

@@ -66,7 +66,8 @@ Zig, V, and Nim programming language standard libraries.")
 (define-public xxhash
   (package
     (name "xxhash")
-    (version "0.8.0")
+    ;; XXX Remove the 'fix-man-page-links phase when updating.
+    (version "0.8.1")
     (source
      (origin
        (method git-fetch)
@@ -75,7 +76,7 @@ Zig, V, and Nim programming language standard libraries.")
              (commit (string-append "v" version))))
        (file-name (git-file-name name version))
        (sha256
-        (base32 "0hpbzdd6kfki5f61g103vp7pfczqkdj0js63avl0ss552jfb8h96"))))
+        (base32 "1h6080lvcr5mpbvy4fhb4i7wvhpy72nrixk3djmpai4hxq41hsnr"))))
     (build-system gnu-build-system)
     (arguments
      `(#:make-flags
@@ -89,6 +90,12 @@ Zig, V, and Nim programming language standard libraries.")
              (string-append "prefix=" (assoc-ref %outputs "out")))
        #:phases
        (modify-phases %standard-phases
+         (add-after 'unpack 'fix-man-page-links
+           ;; https://github.com/Cyan4973/xxHash/issues/647
+           (lambda _
+             (substitute* "Makefile"
+               (("ln -sf \\$\\(MAN\\)")
+                "ln -sf xxhsum.1"))))
          (delete 'configure))))         ; no configure script
     (home-page "https://cyan4973.github.io/xxHash/")
     (synopsis "Extremely fast hash algorithm")