pkgsStatic.gum: fix build (NixOS#398033)

Author: pbsds

pkgs/by-name/gu/gum/package.nix

@@ -23,11 +23,17 @@ buildGoModule rec {
     installShellFiles
   ];
 
-  ldflags = [
-    "-s"
-    "-w"
-    "-X=main.Version=${version}"
-  ];
+  ldflags =
+    [
+      "-s"
+      "-w"
+      "-X=main.Version=${version}"
+    ]
+    ++ lib.optionals (stdenv.hostPlatform.isLinux && stdenv.hostPlatform.isStatic) [
+      "-linkmode=external"
+      "-extldflags"
+      "-static"
+    ];
 
   postInstall = lib.optionalString (stdenv.buildPlatform.canExecute stdenv.hostPlatform) ''
     $out/bin/gum man > gum.1