test: add googletest release-1.8.0 source

We will use the Google Test Framework for testing.

Google Test is not meant to be packaged and used as a system
dependency like other libraries.  Google Test recommends that
it be custom compiled for each project that uses it.  Thus,
we'll keep our own copy of it here and compile it as needed.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>
Reviewed-by: Sean V Kelley <seanvk@posteo.de>
48 files changed