Travis timeout fixes

[varunagrawal]

Travis has been timing out a lot recently due to the increase in unit tests (especially for DEBUG builds).

This PR increases the number of make cores from 2 to 3.
I also removed the sudo requirement since travis has deprecated that.

[jlblancoc]

I'm afraid there are only 2 cores in Travis: https://docs.travis-ci.com/user/reference/overview/#virtualization-environments

So the -j3 has no actual effect...

[dellaert]

Actually that might not be quite true, right? A thread might be blocked on a file resource allowing two other threads to use the cores fully. But proof is in pudding, and @varunagrawal might want to look at the timings in the build to verify...

[dellaert]

See https://stackoverflow.com/questions/15289250/make-j4-or-j8/15295032

[jlblancoc]

That's true...

[jlblancoc]

If you are interested, we could prepare a configuration file for CircleCI instead... from my experience, it's much faster to launch and build... ?

[dellaert]

If you are interested, we could prepare a configuration file for CircleCI instead... from my experience, it's much faster to launch and build... ?

Let's see how the Github actions work?

[varunagrawal]

If we can move to GitHub Actions this weekend, I am completely fine with closing this PR.

Whatever makes me not have to manually restart CI tasks constantly.

[dellaert]

Just merge it. I think it might help a bit