use process start time when checking nested directory changes

[Knagis]

I honestly still have no idea which conditions exactly triggered the issue. But it was reproduced consistently - the root watcher was triggered on a change to the output folder but then the recursive check found some deep folder where it decided to compare mtime to 1 and of course always thought the folder had changed.

I am running on Windows but some colleagues using Macs reported similar issue though I haven't tested if they encountered the same problem.

Even though there likely is a more proper fix possible somewhere, this seems as a safe change to mitigate it.

[codecov]

Codecov Report

Merging #178 (46c763b) into master (c42f625) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #178      +/-   ##
==========================================
+ Coverage   89.15%   89.16%   +0.01%     
==========================================
  Files           6        6              
  Lines        1051     1052       +1     
  Branches      245      245              
==========================================
+ Hits          937      938       +1     
  Misses        114      114              

Impacted Files	Coverage Δ
lib/DirectoryWatcher.js	89.78% <100.00%> (+0.02%)	⬆️

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[alexander-akait]

Please add tests

[Knagis]

Please add tests

unfortunately I don't know the exact scenario that triggers the issue. By the way, the root cause where I could reproduce it was already fixed by @sokra in #179, so this PR could now only serve as a mitigation for some other yet uncaught issue.

[sokra]

I think the PR is no longer needed as this has been fixed by the other PR