Fallback to __FILE__ when initializing global_prefix

[tkf]

pathof(@__MODULE__) cannot be used to find the module path reliably due to JuliaLang/julia#31662. I suggest to fallback to @__FILE__.

Alternatively, a much simpler solution would be to use @__DIR__

global_prefix = Prefix(joinpath(@__DIR__, "..", "global_prefix"))

but this would decrease relocatability #126.

[codecov-io]

Codecov Report

Merging #156 into master will decrease coverage by 0.11%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##           master     #156      +/-   ##
==========================================
- Coverage   56.83%   56.71%   -0.12%     
==========================================
  Files           9        9              
  Lines        1010     1012       +2     
==========================================
  Hits          574      574              
- Misses        436      438       +2

Impacted Files	Coverage Δ
src/BinaryProvider.jl	60% <33.33%> (-40%)	⬇️

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