Don't write one character at a time, it's inefficient

Dependencies

• [2] AEFNBIIW * Merge the GC branch.
• [3] AEKIREIH * Updated hydra_eval_jobs for the new evaluator.
• [4] 4LWGZL33
• [*] 4N5APGRG * Start of a helper tool to evaluate job expressions efficiently.

Change contents

• edit in src/c/hydra-eval-jobs.cc at line 256
  [3.1625]→[2.1297:1336](∅→∅)
  − std::cout.setf(std::ios::unitbuf);