This first step add the infrastructure to test if libc follows semantic
versioning.
In the build step it creates a test file which imports all functions,
constants, etc. that are expected to be public. This file is generated
from the files in the (not yet included) semver directory. These files
include the function and constants expected to be public per target
family, vendor, OS, etc.
See the do_semver function in the build file of libc-test for the
details.
Thomas de Zeeuw