Prepare to run test suite on Azure Pipeline.

* js/vsts-ci: (22 commits)
  test-date: drop unused parameter to getnanos()
  ci: parallelize testing on Windows
  ci: speed up Windows phase
  tests: optionally skip bin-wrappers/
  t0061: workaround issues with --with-dashes and RUNTIME_PREFIX
  tests: add t/helper/ to the PATH with --with-dashes
  mingw: try to work around issues with the test cleanup
  tests: include detailed trace logs with --write-junit-xml upon failure
  tests: avoid calling Perl just to determine file sizes
  README: add a build badge (status of the Azure Pipelines build)
  mingw: be more generous when wrapping up the setitimer() emulation
  ci: use git-sdk-64-minimal build artifact
  ci: add a Windows job to the Azure Pipelines definition
  Add a build definition for Azure DevOps
  ci/lib.sh: add support for Azure Pipelines
  tests: optionally write results as JUnit-style .xml
  test-date: add a subcommand to measure times in shell scripts
  ci: use a junction on Windows instead of a symlink
  ci: inherit --jobs via MAKEFLAGS in run-build-and-tests
  ci/lib.sh: encapsulate Travis-specific things
  ...