libgtest.a and libtinyxm2.a not in lib/<config>

[ptheywood]

CMake is not correctly setting the output location for the static libraries created for googletest and tinyxml2 correctly.

libgtest.a and libtinyxml2.a are being output into lib/ rather than lib/Release for instance (although there is also a copy of libtinyxml2.a in lib/Release alongside the correctly positioned libflamegpu2.a.

I believe the solution is to adjust how we are setting LIBRARY_OUTPUT_DIRECTORY, which is currently being defined in many places iirc (with logic based on which is tha parent).

Once adjusted this needs checking with:

• main repo build
• individual example in main repo
• Standalone example