Use evalFile() instead of parseExprFromFile()

Dependencies

• [2] JUQJHSYJ release.nix: Add `--with-docbook-xsl' to the configure flags for `tarball'.
• [3] 52JSLNC6 * Build fix.
• [4] A4SFSXJW libexpr's symbol table has changed
• [5] WR6LRCAC oops, committed too much
• [6] KBONEPPH configure: Pass `-L/to/nix' as $LDFLAGS, not $LIBS.
• [7] QK2OXCKP hydra/release.nix: move manual to tarball build, restore version in store path for tarball build
• [8] HX4QYOYA add first evaluations tests
• [9] NDJ6PZB7 * Fix symbol to look for.
• [10] 3PNG7NIB Remove trailing whitespace
• [11] POPU2ATH * hydra_scheduler: use eval-jobs.
• [12] FJILMA6G configure: Preserve the user's $CPPFLAGS and $LDFLAGS.
• [13] 2KJFOYGS hydra: Actually check for Nix in `configure'.
• [14] 4N5APGRG * Start of a helper tool to evaluate job expressions efficiently.
• [15] 4LWGZL33
• [16] AEKIREIH * Updated hydra_eval_jobs for the new evaluator.
• [17] OEKXEMU2 hydra: Change the `tarball' job to use `--with-nix'.
• [*] FV2M6MOT hydra: use autoconf/-make
• [*] T4LLYESZ * Nix expression for building Hydra.

Change contents

• replacement in configure.ac at line 70
  [5.248]→[4.0:71](∅→∅)
  − AC_CHECK_LIB([expr], [_ZN3nix9EvalState17parseExprFromFileERKSs], [:],
  [5.248]

  [5.74]
  + AC_CHECK_LIB([expr], [_ZN3nix9EvalState8evalFileERKSsRNS_5ValueE], [:],
• replacement in release.nix at line 37
  [2.23]→[2.23:53](∅→∅)
  − [ "--with-nix=${nix}"
  [2.23]

  [2.53]
  + [ "--with-nix=${nixUnstable}"
• edit in src/c/hydra-eval-jobs.cc at line 287
  [5.881]→[3.81:134](∅→∅)
  − Expr * e = state.parseExprFromFile(releaseExpr);
• replacement in src/c/hydra-eval-jobs.cc at line 288
  [5.2815]→[5.2815:2841](∅→∅)
  − state.mkThunk_(v, e);
  [5.2815]

  [5.1624]
  + state.evalFile(releaseExpr, v);