Its possible that idivl overflows (due to large delta stored in usdiff,
valid scenario).

Create an exception handler to catch the overflow exception (division by zero
is protected by vcpu->arch.virtual_tsc_khz check), and interpret it accordingly
(delta is larger than USEC_PER_SEC).

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=969644Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>