warzone2100: fix build

I'm not sure how the build broke[1] or how it worked before, but
the problem is zip is being used in place of p7zip, which obviously
fail as the flags have different meanings.

[1]: https://hydra.nixos.org/build/143354937

(cherry picked from commit 302d6b1b8b)

pkgs/games/warzone2100/default.nix

@@ -3,7 +3,7 @@
 , fetchurl
 , cmake
 , ninja
-, zip
+, p7zip
 , pkg-config
 , asciidoctor
 , gettext
@@ -68,7 +68,7 @@ stdenv.mkDerivation rec {
     pkg-config
     cmake
     ninja
-    zip
+    p7zip
     asciidoctor
     gettext
     shaderc