Fix build for new nixUnstable

Dependencies

• [2] 3PNG7NIB Remove trailing whitespace
• [3] F57YJP5P Build against latest Nix
• [4] A63IHCMX * Register GC roots properly.
• [5] AEKIREIH * Updated hydra_eval_jobs for the new evaluator.
• [6] HX4QYOYA add first evaluations tests
• [7] 7YCFGMZB * Report evaluation errors per job, and don't bail out if a job fails
• [8] FJILMA6G configure: Preserve the user's $CPPFLAGS and $LDFLAGS.
• [9] SM5M2J3A Pass inputs to release expressions using -I
• [10] 4LWGZL33
• [11] A4SFSXJW libexpr's symbol table has changed
• [12] KBONEPPH configure: Pass `-L/to/nix' as $LDFLAGS, not $LIBS.
• [13] MIC2O6ZF Use evalFile() instead of parseExprFromFile()
• [14] D4MVPDFM nix's libs live in $out/lib now, not $out/nix/lib
• [15] EBG4P4SY Doh - clear $NIX_PATH properly
• [16] KD5237CU * eval-jobs now efficiently evaluates all Hydra jobs from a
• [17] 2KJFOYGS hydra: Actually check for Nix in `configure'.
• [18] NDJ6PZB7 * Fix symbol to look for.
• [19] WR6LRCAC oops, committed too much
• [20] 4N5APGRG * Start of a helper tool to evaluate job expressions efficiently.
• [*] FV2M6MOT hydra: use autoconf/-make

Change contents

• replacement in configure.ac at line 72
  [4.248]→[3.0:75](∅→∅)
  − AC_CHECK_LIB([nixexpr], [_ZN3nix9EvalState8evalFileERKSsRNS_5ValueE], [:],
  [4.248]

  [4.74]
  + AC_CHECK_LIB([nixexpr], [_ZN3nix9EvalStateC1ERKSt4listISsSaISsEE], [:],
• replacement in src/c/hydra-eval-jobs.cc at line 236
  [4.113]→[4.570:591](∅→∅),[2.807]→[4.570:591](∅→∅),[4.570]→[4.570:591](∅→∅)
  − EvalState state;
  [2.807]

  [4.591]
  + /* FIXME: hack */

  + Strings searchPath;

  + Strings args2;

  + for (Strings::iterator i = args.begin(); i != args.end(); ) {

  + string arg = *i++;

  + if (!parseSearchPathArg(arg, i, args.end(), searchPath))

  + args2.push_back(arg);

  + }

  + args = args2;

  + EvalState state(searchPath);
• edit in src/c/hydra-eval-jobs.cc at line 271
  [4.582]→[4.141:219](∅→∅)
  − else if (parseSearchPathArg(arg, i, args.end(), state))

  − ;