ARROW-5498: [C++][CI] Fix Flatbuffers related error with MinGW

[kou]

We should send a pull request that adds -DCMAKE_BUILD_TYPE=Release to
https://github.com/msys2/MINGW-packages/blob/master/mingw-w64-flatbuffers/PKGBUILD
.

[codecov-io]

Codecov Report

Merging #4465 into master will increase coverage by 0.92%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4465      +/-   ##
==========================================
+ Coverage   88.26%   89.19%   +0.92%     
==========================================
  Files         846      696     -150     
  Lines      103357    91516   -11841     
  Branches     1253        0    -1253     
==========================================
- Hits        91229    81627    -9602     
+ Misses      11881     9889    -1992     
+ Partials      247        0     -247

Impacted Files	Coverage Δ
go/arrow/ipc/writer.go
go/arrow/math/uint64_amd64.go
go/arrow/memory/memory_avx2_amd64.go
go/arrow/ipc/file_reader.go
js/src/enum.ts
go/arrow/array/builder.go
js/src/Arrow.node.ts
js/src/schema.ts
go/arrow/type_traits_boolean.go
js/src/ipc/node/writer.ts
... and 141 more

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[wesm]

+1

[kou]

Done: msys2/MINGW-packages#5471