6136a96cdf631f824fb89cf2720422787439acc9 ci: Rename RUN_CI_ON_HOST to DANGER_RUN_CI_ON_HOST (Hennadii Stepanov)
97ba77aa8e58c3c7ff767e6ca804d0e46370e5dc ci: Add native s390x (Hennadii Stepanov)
Pull request description:
Unlike the Docker wrapped solution (#17591) this PR suggests running on host system directly.
This approach makes builds quick and stable (see: #18106).
The excerpt from the Travis log:
```
...
Running on host system without docker wrapper
...
Byte Order: Big Endian
...
```
ACKs for top commit:
MarcoFalke:
ACK 6136a96cdf631f824fb89cf2720422787439acc9
Tree-SHA512: 1b591de13e38d10a35217e1de11cbd648a359d18d16eed166fac18ea5788b58cc9fc6d407086ed342b99e57e479efd951a0ea693710177e500eb116316b9a788