zile: disable help2man for cross builds

Ericson2314 · Ericson2314 · commit 28e4975bd1c2 · 2017-09-06T00:31:25.000-04:00
@dezgeg caught my error--the issue isn't building help2man, but running it on cross-compiled binaries. This effectively reverts 0825f30 as far as behavior is concerned, but keeps the removal of `crossAttrs`.
diff --git a/pkgs/applications/editors/zile/default.nix b/pkgs/applications/editors/zile/default.nix
@@ -9,7 +9,12 @@ stdenv.mkDerivation rec {
   };
 
   buildInputs = [ pkgconfig ncurses boehmgc ];
-  nativeBuildInputs = [ help2man perl ];
+  nativeBuildInputs = [ perl ]
+    # `help2man' wants to run Zile, which won't work when the
+    # newly-produced binary can't be run at build-time.
+    ++ stdenv.lib.optional
+         (stdenv.hostPlatform == stdenv.buildPlatform)
+         help2man;
 
   # Tests can't be run because most of them rely on the ability to
   # fiddle with the terminal.
