gnu: Add go-github-com-spf13-pflag.

* gnu/packages/golang.scm (go-github-com-spf13-pflag): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/golang.scm

@@ -1673,3 +1673,32 @@ incoming requests with their respective handler.")
        "Replace uses of the @code{time} package with the
 @code{clockwork.Clock} interface instead.")
       (license license:asl2.0))))
+
+(define-public go-github-com-spf13-pflag
+  (let ((commit "4f9190456aed1c2113ca51ea9b89219747458dc1")
+        (revision "0"))
+    (package
+      (name "go-github-com-spf13-pflag")
+      (version (git-version "0.0.0" revision commit))
+      (source
+        (origin
+          (method git-fetch)
+          (uri (git-reference
+                 (url "https://github.com/spf13/pflag.git")
+                 (commit commit)))
+          (file-name (git-file-name name version))
+          (sha256
+            (base32
+              "12vrlcsbwjqlfc49rwky45mbcj74c0kb6z54354pzas6fwzyi1kc"))))
+      (build-system go-build-system)
+      (arguments
+        '(#:import-path "github.com/spf13/pflag"))
+      (home-page "https://github.com/spf13/pflag")
+      (synopsis "Replacement for Go's @code{flag} package")
+      (description
+       "Pflag is library to replace Go's @code{flag} package.  It implements
+POSIX/GNU-style command-line options with double hyphens.  It is is compatible
+with the
+@uref{https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html,
+GNU extensions} to the POSIX recommendations for command-line options.")
+      (license license:bsd-3))))