maint: improve debug of libvirt-{qemu,lxc} apis

maint: improve debug of libvirt-{qemu,lxc} apis

I noticed that the virDomainQemuMonitorCommand debug output wasn't
telling me the name of the domain it was working on.  While it was
easy enough to determine which pointer matches the domain based on
other log messages, it is nicer to be consistent.

* src/util/viruuid.h (VIR_UUID_DEBUG): Moved here from...
* src/libvirt.c (VIR_UUID_DEBUG): ...here.
(VIR_ARG15, VIR_HAS_COMMA, VIR_DOMAIN_DEBUG_EXPAND)
(VIR_DOMAIN_DEBUG_PASTE, VIR_DOMAIN_DEBUG_0, VIR_DOMAIN_DEBUG_1)
(VIR_DOMAIN_DEBUG_2, VIR_DOMAIN_DEBUG): Move...
* src/datatypes.h: ...here.
* src/libvirt-qemu.c (virDomainQemuMonitorCommand)
(virDomainQemuAgentCommand): Better debug messages.
* src/libvirt-lxc.c (virDomainLxcOpenNamespace): Likewise.

Signed-off-by: Eric Blake <eblake@redhat.com>