TST: fix failure of test for signal.colvolve on 32-bit platforms.

Partial backport of scipygh-7517.

REL: tag v0.19.0

REL: tag 0.19.0rc2

REL: tag scipy 0.19.0rc1

REL: tag scipy 0.18.1

REL: Scipy 0.18.0-1 --- same content as v0.18.0 but new tag for Zenodo

REL: tag scipy 0.18.0

REL: release candidate 2 for 0.18.0

REL: release candidate 0.18.0rc1

REL: release 0.17.1