Re: [libvirt] [PATCH v3] Fix up basic migration.

Basic live migration was broken by the commit that added non-shared block support in two ways: 1) It added a virCheckFlags() to doNativeMigrate(). Besides the fact that typical usage of virCheckFlags() is in driver entry points, and doNativeMigrate() is not an entry point, it was missing important flags like VIR_MIGRATE_LIVE. Move the virCheckFlags to the top-level qemuDomainMigratePrepare2 and friends. 2) It also added a memory leak in qemuMonitorTextMigrate() by not freeing the memory used by virBufferContentAndReset(). This is fixed by storing the pointer in a temporary variable and freeing it at the end. With this patch in place, normal live migration works again.

v3: Instead of the churn for virCheckFlagsUI and UL, instead always promote flags to an unsigned long and always use %lx for the fprintf.