dsniff: unbreak the build

We revert to using GCC 9 for compilation, in order to work around a GCC 10 bug
resulting in a segfault when compiling.

The alternative would be to restrict to optimization level -O1, but this
disables fortify.

pkgs/tools/networking/dsniff/default.nix

@@ -1,6 +1,10 @@
-{ stdenv, fetchFromGitLab, autoreconfHook, libpcap, db, glib, libnet, libnids, symlinkJoin, openssl
+{ gcc9Stdenv, lib, fetchFromGitLab, autoreconfHook, libpcap, db, glib, libnet, libnids, symlinkJoin, openssl
 , rpcsvc-proto, libtirpc, libnsl
 }:
+
+# We compile with GCC 9 since GCC 10 segfaults on the code
+# (see https://bugzilla.redhat.com/show_bug.cgi?id=1862809).
+
 let
   /*
   dsniff's build system unconditionnaly wants static libraries and does not
@@ -38,7 +42,7 @@ let
     inherit (openssl) name;
     paths = with openssl.override { static = true; }; [ out dev ];
   };
-in stdenv.mkDerivation rec {
+in gcc9Stdenv.mkDerivation rec {
   pname = "dsniff";
   version = "2.4b1";
   # upstream is so old that nearly every distribution packages the beta version.
@@ -71,7 +75,7 @@ in stdenv.mkDerivation rec {
     "--with-openssl=${ssl}"
   ];
 
-  meta = with stdenv.lib; {
+  meta = with lib; {
     description = "collection of tools for network auditing and penetration testing";
     longDescription = ''
       dsniff, filesnarf, mailsnarf, msgsnarf, urlsnarf, and webspy passively monitor a network for interesting data (passwords, e-mail, files, etc.). arpspoof, dnsspoof, and macof facilitate the interception of network traffic normally unavailable to an attacker (e.g, due to layer-2 switching). sshmitm and webmitm implement active monkey-in-the-middle attacks against redirected SSH and HTTPS sessions by exploiting weak bindings in ad-hoc PKI.