php: Enable SSL via buildInputs

The old way doesn't seem to work with multiple outputs.
TODO: this seems to be a recurring pattern with openssl, maybe the
splitting isn't done correctly?

pkgs/development/interpreters/php/default.nix

@@ -146,7 +146,7 @@ let
         };
 
         openssl = {
-          configureFlags = ["--with-openssl=${openssl}"];
+          configureFlags = ["--enable-openssl"];
           buildInputs = [openssl];
         };