qemu_tpm: Start swtpm(8) daemon with --terminate switch

Launch swtpm(8) with the --terminate switch, which guarantees that
the daemon will shut itself down when QEMU dies (current behavior).
We had so far been getting this "for free" (i.e. without --terminate)
due to a defect in upstream's connection handling logic [1], on which
libvirt should not rely since it will eventually be fixed. Adding
--terminate preserves and guarantees the current behavior.

[1] https://github.com/stefanberger/swtpm/pull/509

Signed-off-by: Nick Chevsky <nchevsky@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_tpm.c

@@ -576,6 +576,8 @@ qemuTPMEmulatorBuildCommand(virDomainTPMDef *tpm,
     virCommandAddArg(cmd, "--log");
     virCommandAddArgFormat(cmd, "file=%s", tpm->data.emulator.logfile);
 
+    virCommandAddArg(cmd, "--terminate");
+
     virCommandSetUID(cmd, swtpm_user);
     virCommandSetGID(cmd, swtpm_group);