Cosmos: Tell Travis CI to Ignore Libgraph for C Build

[arnavb]

This is a(n):

• [ ] New algorithm
• [ ] Update to an existing algorithm
• [x] Error
• [ ] Proposal to the Repository

Details:

• Currently, our TravisCI build for C fails because an external library, libgraph-1.0.2, contains numerous errors. Because of this, the build is unable to succeed.
• I propose adding the change to the continuous integration so that this library is ignored, and even if it contains errors, the build should pass. (This makes sense, since a bad build isn't our problem anyways).

Anyone willing to take this on?

[parulagg27]

Hi! I would like to work on this issue.

[arnavb]

@parulagg27 Go for it! It should only be a small change to the .travis.yml! Make sure to reference this issue when you are done!

[arnavb]

@parulagg27 Instead of referring to this issue in your PR, please refer to #3221, which is the same issue.