fa330d8fed5a02349440be170af3b443c1321b4b ci: Avoid invoking curl on the host (MarcoFalke)
Pull request description:
The only requirement for the ci system are the programs `docker.io` and `bash`. However, the mac cross build invokes `curl` on the host. Fix that.
Before:
```
$ FILE_ENV="./ci/test/00_setup_env_mac.sh" ./ci/test_run_all.sh
...
./ci/test/05_before_script.sh: line 22: curl: command not found
```
After:
```
... (command passes)
ACKs for top commit:
promag:
ACK fa330d8fed5a02349440be170af3b443c1321b4b.
Tree-SHA512: 49120fd671a48a6599dd6c34f6d3502a6e9f84b4476061cab06f55cba374d8188f53b9b41363e90f5fafb0074767b581f30bd2545c0b6934580a7eccfa1ef5c4