[impl] add support for compilation from emscripten

[biojppm]

see biojppm/c4core#52

[codecov]

Codecov Report

Merging #176 (78f3a6e) into master (4a8f54a) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 78f3a6e differs from pull request most recent head dd997ec. Consider uploading reports for the commit dd997ec to get more accurate results

@@           Coverage Diff           @@
##           master     #176   +/-   ##
=======================================
  Coverage   96.35%   96.35%           
=======================================
  Files          63       63           
  Lines       12843    12845    +2     
=======================================
+ Hits        12375    12377    +2     
  Misses        468      468           

Impacted Files	Coverage Δ
samples/quickstart.cpp	99.51% <100.00%> (+<0.01%)	⬆️

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