gem-config: add pcaprub

pkgs/development/ruby-modules/gem-config/default.nix

@@ -21,7 +21,7 @@
 , libiconv, postgresql, v8_3_16_14, clang, sqlite, zlib, imagemagick
 , pkgconfig , ncurses, xapian_1_2_22, gpgme, utillinux, fetchpatch, tzdata, icu, libffi
 , cmake, libssh2, openssl, mysql, darwin, git, perl, gecode_3, curl
-, libmsgpack, qt48, libsodium, snappy, libossp_uuid, lxc
+, libmsgpack, qt48, libsodium, snappy, libossp_uuid, lxc, libpcap
 }@args:
 
 let
@@ -135,6 +135,10 @@ in
     buildInputs = [ curl ];
   };
 
+  pcaprub = attrs: {
+    buildInputs = [ libpcap ];
+  };
+
   pg = attrs: {
     buildFlags = [
       "--with-pg-config=${postgresql}/bin/pg_config"