rethinkdb: Remove pin on boost 1.55 and remove gperf dependency

pkgs/servers/nosql/rethinkdb/default.nix

···
-{ stdenv, fetchurl, which, protobuf, gperftools
-, boost, zlib, curl, python, m4, icu, jemalloc }:
+{ stdenv, fetchurl, which, m4, python
+, protobuf, boost, zlib, curl, openssl, icu, jemalloc
+}:
 
 stdenv.mkDerivation rec {
   name = "rethinkdb-${version}";
···
     patchShebangs .
   '';
 
-  configureFlags = "--lib-path ${gperftools}/lib --lib-path ${jemalloc}/lib";
+  configureFlags = [
+    "--with-jemalloc"
+    "--lib-path=${jemalloc}/lib"
+  ];
 
-  buildInputs = [ protobuf boost zlib curl icu jemalloc ];
+  buildInputs = [ protobuf boost zlib curl openssl icu jemalloc ];
 
   nativeBuildInputs = [ which m4 python ];
+
+  enableParallelBuilding = true;
 
   meta = {
     description = "An open-source distributed database built with love";

pkgs/top-level/all-packages.nix

···
 
   restund = callPackage ../servers/restund {};
 
-  rethinkdb = callPackage ../servers/nosql/rethinkdb {
-    boost = boost155;
-  };
+  rethinkdb = callPackage ../servers/nosql/rethinkdb { };
 
   rippled = callPackage ../servers/rippled {
     boost = boost157;