Lock builds for a shorter amount of time

Dependencies

• [2] ENXUSMSV Make concurrency more robust
• [3] 24BMQDZA Start of single-process hydra-queue-runner
• [4] NJJ7H64S Very basic multi-threaded queue runner
• [5] YZAI5GQU Implement a database connection pool

Change contents

• edit in src/hydra-queue-runner/hydra-queue-runner.cc at line 424
  [3.1944]→[2.1294:1605](∅→∅)
  − #if 0

  − {

  − auto runnable_(runnable.lock());

  − auto builds_(builds.lock());

  − auto steps_(steps.lock());

  − printMsg(lvlError, format("%1% builds, %2% steps, %3% runnable steps")

  − % builds_->size()

  − % steps_->size()

  − % runnable_->size());

  − }

  − #endif

  −
• edit in src/hydra-queue-runner/hydra-queue-runner.cc at line 435
  [3.9907]→[2.2010:2048](∅→∅)
  − auto builds_(builds.lock());

  −
• edit in src/hydra-queue-runner/hydra-queue-runner.cc at line 436
  [2.2087]

  [2.2087]
  + auto builds_(builds.lock());