Fix versioned dylib discovery.

[maleadt]

Supersedes #483, fixes #482.

[codecov]

Codecov Report

Merging #486 into master will decrease coverage by 0.06%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #486      +/-   ##
==========================================
- Coverage   80.55%   80.49%   -0.07%     
==========================================
  Files         166      166              
  Lines        8857     8864       +7     
==========================================
  Hits         7135     7135              
- Misses       1722     1729       +7     

Impacted Files	Coverage Δ
deps/discovery.jl	68.22% <0.00%> (-2.59%)	⬇️

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