bhyve/tpm: create crb thread for sending tpm commands

[corvink]

Summary

Commands send to a tpm are very slow. They can take up to several
seconds for completion. For that reason, create a thread which issues
the commands to the tpm device.

[markj]

usr.sbin/bhyve/tpm_intf_crb.c

214

296

The mutex and condvar don't get destroyed anywhere.

310

Why not just write pthread_set_name_np(crb->thread, "tpm_intf_crb");?

331

Don't you need to wake up the thread here?

[corvink]

• destroy cond and mutex
• wakeup thread on destroy

[markj]

usr.sbin/bhyve/tpm_intf_crb.c

292

warn/warnx/warc/err/errx/errc always append a newline.

292

pthread_* returns an error number upon failure, so you can get a better error message with warnc(error, "%s: failed to init mutex", __func__);. Same below.