mod_wsgi: fixed build on Darwin

The configure script had an hard-coded impure path to the lipo binary. If that
binary was found -- and it was --, then the script decided to pass an invalid
"-arch i386" flag to libtool, which subsequently failed. There is probably
another way to pass that -arch flag, but I didn't look hard because it's
redundant anyway.

svn path=/nixpkgs/trunk/; revision=24530

pkgs/servers/http/apache-modules/mod_wsgi/default.nix

@@ -11,7 +11,9 @@ stdenv.mkDerivation {
   buildInputs = [ apacheHttpd python ];
 
   patchPhase = ''
-    sed -r -i "s|^LIBEXECDIR=.*$|LIBEXECDIR=$out/modules|" configure
+    sed -r -i -e "s|^LIBEXECDIR=.*$|LIBEXECDIR=$out/modules|" \
+      ${if stdenv.isDarwin then "-e 's|/usr/bin/lipo|lipo|'" else ""} \
+      configure
   '';
 
   meta = {