Introduce --with-tpm2 for ./configure to enable building with
TPM 2 functionality. Delay the building of TPM 2 code until more
patches are applied and the vTPM state that's created has a chance
of being backwards compatible.
Extend the libtpms API to allow user to choose version of TPM.
Missing functionality at this point:
- TPM 2 needs to be extended to serialize and deserialize its volatile state
- Handling of the establishment bit
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>