compiler: allow for loops with empty condition

[fyrchik]

Easiest way to make infinite loops.

[codecov]

Codecov Report

Merging #799 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #799      +/-   ##
==========================================
+ Coverage   66.75%   66.76%   +<.01%     
==========================================
  Files         141      141              
  Lines       12963    12964       +1     
==========================================
+ Hits         8654     8655       +1     
  Misses       3899     3899              
  Partials      410      410

Impacted Files	Coverage Δ
pkg/compiler/codegen.go	87.78% <100%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 198fffb...f0b6f78. Read the comment docs.