[C++] Arrow dynamic libraries are missed on run of unit tests on Windows

[asfimport]

Output DLL and PDB files are not copied to root build output directory.
Because of above DLLs are not found by dependencies loader and unit tests are failed to start.

Reporter: Max Risuhin / @maxhora
Assignee: Max Risuhin / @maxhora

Related issues:

• [C++] Build and run full test suite in Appveyor (Blocked)

_{Note: This issue was originally created as ARROW-699. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 449
#449