rocksdb: disable on i686 (ZHF)

pkgs/development/libraries/rocksdb/default.nix

···
     homepage = http://rocksdb.org;
     description = "A library that provides an embeddable, persistent key-value store for fast storage";
     license = licenses.bsd3;
-    platforms = platforms.all;
+    platforms = platforms.allBut [ "i686-linux" ];
     maintainers = with maintainers; [ wkennington ];
   };
 }