Restore the optimization done in
HEAD^{/Speed up the generation of storage format test cases}
which was lost during refactoring made when adding support for
implicit usage flags.
There are still more than one call to the C compiler, but the extra
calls are only for some key usage test cases.
This is an internal refactoring. This commit does not change the
output of generate_psa_tests.py
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
