gnu: Add go-github-com-pmezard-go-difflib.

* gnu/packages/golang.scm (go-github-com-pmezard-go-difflib): New variable.

gnu/packages/golang.scm

@@ -2490,6 +2490,28 @@ building command line apps in Go.  The goal is to enable developers to write
 fast and distributable command line applications in an expressive way.")
     (license license:expat)))
 
+(define-public go-github-com-pmezard-go-difflib
+  (package
+    (name "go-github-com-pmezard-go-difflib")
+    (version "1.0.0")
+    (source (origin
+              (method git-fetch)
+              (uri (git-reference
+                    (url "https://github.com/pmezard/go-difflib")
+                    (commit (string-append "v" version))))
+              (file-name (git-file-name name version))
+              (sha256
+               (base32
+                "0c1cn55m4rypmscgf0rrb88pn58j3ysvc2d0432dp3c6fqg6cnzw"))))
+    (build-system go-build-system)
+    (arguments
+     '(#:import-path "github.com/pmezard/go-difflib/difflib"
+       #:unpack-path "github.com/pmezard/go-difflib/"))
+    (home-page "https://github.com/pmezard/go-difflib")
+    (synopsis "Go diff implementation")
+    (description "This package provides unified and context-aware diffs in Go.")
+    (license license:bsd-3)))
+
 (define-public go-github-com-whyrusleeping-json-filter
   (let ((commit "ff25329a9528f01c5175414f16cc0a6a162a5b8b")
         (revision "0"))