TravisCI for ppc64le and suppression file update for Dilithium

[bhess]

(1)
Simple TravisCI integration for ppc64le

(2)
Minor suppression file update for Dilithium after a constant-time check on ppc64le (see #1037):
(i) two line numbers changed, (ii) using explicit function name (fun:rej_uniform) for generic Dilithium

The CI log with reports is available here: ppc64le.txt

The SPHINCS+ reports are documented separately in #1038.

The reported issues (except #1038) should also be reproducible using the constant-time-x64-extensions / constant-time-x64 circleci jobs. After this fix, the constant-time checks pass on x86_64 / ppc64le, except BIKE that will have to be handled separately.

• Does this PR change the input/output behaviour of a cryptographic algorithm (i.e., does it change known answer test values)? (If so, a version bump will be required from x.y.z to x.(y+1).0.)
• Does this PR change the the list of algorithms available -- either adding, removing, or renaming? (If so, PRs in OQS-OpenSSL, OQS-BoringSSL, and OQS-OpenSSH will also be required by the time this is merged.)

[bhess]

TravisCI seems to have moved from travis-ci.org to travis-ci.com. Only repository owners are able to migrate repos to travis-ci.com. @dstebila are you able to do this for liboqs by clicking "Migrate" here? https://travis-ci.com/github/open-quantum-safe/liboqs

[dstebila]

TravisCI seems to have moved from travis-ci.org to travis-ci.com. Only repository owners are able to migrate repos to travis-ci.com. @dstebila are you able to do this for liboqs by clicking "Migrate" here? https://travis-ci.com/github/open-quantum-safe/liboqs

Done.