cmake style fixes

Summary: I was trying to fix our out-of-tree builds, but gave up and was left with these good fixes

Reviewed By: @JoelMarcey

Differential Revision: D1572883
only run quick tests on travis

Summary: while I was in there I deleted a bunch of commented out lines that didn't seem to add anything of value to the config

```
# Sadly, travis only gives up 50 minutes to compile and run our tests. The
# compilation machines usually have a bunch of CPUs but very little RAM so gcc
# dies trying to compile some of our files if we do more than -j 6. So, with -j
# 6 that takes ~40 minutes, leaving only 10 minutes to test. The only thing we
# can fit in that time is the quick tests in no-repo mode. So basically this is
# a smoke test (did it compile and not segfault immediately) instead of a real
# test run. Please check out the attached phabricator to your PR for full unit
# test coverage.
```

Reviewed By: @fredemmott

Differential Revision: D1575816
Implement Memcached::resetServerList()

Summary: Fixes #3615
Closes https://github.com/facebook/hhvm/pull/3827

Reviewed By: @ptarjan

Differential Revision: D1572738
Fix incorrect index in arm cgShuffle

Reviewed By: @swtaarrs

Differential Revision: D1575213