tests: add test configuration via environment variables
tests: add test configuration via environment variables

Allow the test type to be specified by the LIBSECCOMP_TSTCFG_TYPE
environment variable.

Signed-off-by: Paul Moore <a027184a55211cd23e3f3094f1fdc728df5e0500@paul-moore.com>

seccomp/libseccomp,seccomp/libseccomp,seccomp/libseccomp