Fix tests failing with the XCode generator.

XCode puts generated targets into CMAKE_CFG_INTDIR, which is calculated
at built-time, so add a small shim to hoist that out and determine it
at verify-test time.
Update travis.yml to include Makefile and Ninja generators
Merge pull request #9 from smspillaz/tooling-find-package-cmake-util.item_9

Fix tests failing with the XCode generator.