do not run public headers build test on generated headers
While we can argue if generated files should be tested the issue here is that atm there is a different set of tests running between these two scenarioes
make configure
make
make configure
make test_public_headers_build
vs
make configure
make test_public_headers_build
The continue
in this MR skips files from the build area during globbing (that don't exist in the latter example, but do exist in the former).
Edited by Paul Seyfert