qemu: fix domain memory 'last-update' timestamp

This fixes commit 200a40f9 which introduced 'last-update' timestamp.
Signed-off-by: NDerbyshev Dmitry <dderbyshev@virtuozzo.com>
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

include/libvirt/libvirt-domain.h

@@ -609,7 +609,7 @@ typedef enum {
      */
     VIR_DOMAIN_MEMORY_STAT_USABLE          = 8,
 
-    /* Timestamp of the last update of statistics */
+    /* Timestamp of the last update of statistics, in seconds. */
     VIR_DOMAIN_MEMORY_STAT_LAST_UPDATE     = 9,
 
     /*

tools/virsh.pod

@@ -821,6 +821,7 @@ B<Explanation of fields>:
   rss               - Resident Set Size of the running domain's process (in kB)
   usable            - The amount of memory which can be reclaimed by balloon
 without causing host swapping (in KB)
+  last-update       - Timestamp of the last update of statistics (in seconds)
 
 For QEMU/KVM with a memory balloon, setting the optional I<--period> to a
 value larger than 0 in seconds will allow the balloon driver to return