Fix Arm linux builds, allow adding version suffix, and add automatic linux build target testing

[bradgrantham-lunarg]

Fix Arm linux builds, allow setting a vendor-specific version suffix when building, and add a Travis-CI build automation file to help prevent further breakage of less commonly tested linux platforms. Hopefully the main repo can add integration with Travis-CI (free for open source projects) so this check is run for every commit.

This is a resubmit of #543, which I merged prematurely and then had to revert.