ARROW-2990: [GLib] Support building with rpath-ed Arrow C++ on macOS

[kou]

No description provided.

[codecov-io]

Codecov Report

Merging #2374 into master will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2374      +/-   ##
==========================================
+ Coverage   84.49%   84.51%   +0.02%     
==========================================
  Files         293      293              
  Lines       45329    45329              
==========================================
+ Hits        38301    38312      +11     
+ Misses       6997     6990       -7     
+ Partials       31       27       -4

Impacted Files	Coverage Δ
go/arrow/math/float64_sse4_amd64.go	0% <0%> (-100%)	⬇️
go/arrow/memory/memory_sse4_amd64.go	0% <0%> (-100%)	⬇️
go/arrow/math/uint64_sse4_amd64.go	0% <0%> (-100%)	⬇️
go/arrow/math/int64_sse4_amd64.go	0% <0%> (-100%)	⬇️
go/arrow/math/float64_amd64.go	33.33% <0%> (ø)	⬆️
go/arrow/math/int64_amd64.go	33.33% <0%> (ø)	⬆️
go/arrow/math/uint64_amd64.go	33.33% <0%> (ø)	⬆️
cpp/src/arrow/util/thread-pool-test.cc	99.45% <0%> (+0.54%)	⬆️
go/arrow/math/math_amd64.go	36.84% <0%> (+5.26%)	⬆️
go/arrow/memory/memory_amd64.go	42.85% <0%> (+14.28%)	⬆️
... and 4 more

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[wesm]

+1. Thanks @kou!

[xhochy]

Sadly this does not resolve it for me but breaks with a new problem: https://issues.apache.org/jira/browse/ARROW-3086