x86: move basic vmx tests into separate test cases

By default every vmx kvm-unit-test runs a series of tests at startup.
This patch moves those startup tests into test cases which are only run
when requested.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20170421005004.137260-4-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>