Testing takes quite long. For now, use by default only normal variant.
SDB variant is not much used and pkcs11 variant is failing now. Keep
ability to enable variants by parameter:
TEST_VARIANTS="normal sdb pkcs11"
bind-devel should now provide all dependencies required. Omit explicitl
requirements for building. Drop atf building support, since upstream
moved to cmocka.
Make it possible to skip some test using parameter. In some cases, just
single pass is required.
Also fix case when no known defects are specified for a variant.