qemuMonitorJSONMigrate: Extract flags prior to constructing command
qemuMonitorJSONMigrate: Extract flags prior to constructing command

The migration API takes specific flags which are then converted to
boolean parameters for the command. Extract the flag into helper
variables rather than using ternary operators while constructing the
command itself.

Signed-off-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,zippy2/libvirt,olafhering/libvirt,crobinso/libvirt,libvirt/libvirt,olafhering/libvirt,libvirt/libvirt,zippy2/libvirt,jfehlig/libvirt,zippy2/libvirt,libvirt/libvirt,crobinso/libvirt,jfehlig/libvirt,zippy2/libvirt,olafhering/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt