configury: avoid spurious .travis.yml regeneration.
configury: avoid spurious .travis.yml regeneration.

* m4/slingshot.m4 (SS_CONFIG_TRAVIS): Use cp instead of mv to
ensure the .travis.yml timestamp is updated, avoiding spurious
remakes on multiple make reruns.

Signed-off-by: Gary V. Vaughan <f9023000f29773649f3850298becb9544b5fd6a9@gnu.org>

gvvaughan/slingshot