Revert "Workaround to Travis-CI Wine/Mingw build hanging occasionally"

Summary:
This reverts D497. It doesn't provide any value since we don't do Travis
anymore, and the Makefile.test.include changes may provide some nuisances
down the road.

Test Plan: make check

Reviewers: deadalnix, Fabien, jasonbcox, #bitcoin_abc

Reviewed By: deadalnix, #bitcoin_abc

Subscribers: CCulianu

Differential Revision: https://reviews.bitcoinabc.org/D3537