anchor.diff:  
     preConfigure = "cd nss";
   
  -  makeFlags = [
  +  makeFlags = let
  +    cpu = stdenv.hostPlatform.parsed.cpu.name;
  +  in [
       "NSPR_INCLUDE_DIR=${nspr.dev}/include"
       "NSPR_LIB_DIR=${nspr.out}/lib"
       "NSDISTMODE=copy"
  
positive.code: { stdenv, fetchurl, nspr, perl, zlib, sqlite, fixDarwinDylibNames }:
  
  let
    nssPEM = fetchurl {
  
negative.code:     "NSS_ENABLE_ECC=1"
      "USE_SYSTEM_ZLIB=1"
      "NSS_USE_SYSTEM_SQLITE=1"
      "NATIVE_CC=${buildPackages.stdenv.cc}/bin/cc"
      "OS_TEST=${cpu}"
      "CPU_ARCH=${cpu}"
    ] ++ stdenv.lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) [
      "CROSS_COMPILE=1"
      "NSS_DISABLE_GTESTS=1" # don't want to build tests when cross-compiling
    ] ++ stdenv.lib.optional stdenv.is64bit "USE_64=1"
      ++ stdenv.lib.optional stdenv.isDarwin "CCC=clang++";
  
  