This patch moves static last_delta variable into timers_state
structure to allow correct vmstate operations with icount shift=auto enabled.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <161701335066.1180180.7104085247702343395.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>