Add Mesos formula

Builds on #24105 and updates it to the current Mesos release (0.19.0).
Mesos compiles on clang since a few versions ago so I removed the compiler checks.
Thanks, as I mentioned before there isn't a meaningful test for Mesos that follows this pattern - execute or compile a file with the program that is going to be installed.
Mesos runs as a daemon and programs (schedulers) connect to it via HTTP. So at a minimum I need to start a deamon, run an example program, then kill the daemon. I can hack something together of course but would appreciate some guidance because this will be very error prone if not implemented carefully.
Can you point me to an example test that is closer to a scenario like this?