Fix ASM output for the zig compiler

[haze]

This fixes #1689 by using the suggestion @andrewrk made.

This also properly disables the demangler for compilers that don't provide one.
(There was a bug where path.normalize would turn an empty string into ..)

[codecov]

Codecov Report

Merging #1711 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #1711      +/-   ##
=========================================
+ Coverage   56.29%   56.3%   +<.01%     
=========================================
  Files          64      64              
  Lines        5020    5021       +1     
=========================================
+ Hits         2826    2827       +1     
  Misses       2194    2194

Impacted Files	Coverage Δ
lib/compiler-finder.js	40% <100%> (+0.37%)	⬆️

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[RubenRBS]

Thanks for taking the time to fix the Zig compilers :)
Also, great catch with the demangler fix. I'll merge now and it should hit the live site in the next few days