Report pg/history from OSD on every degraded activation

Required to prevent data loss due to activation of an OSD with older data
when PG OSD set change doesn't occur. I.e. fixes the simplest case:
- Run 2 OSDs with 1 PG
- Start writing into the PG
- Stop OSD 2
- Stop OSD 1
- Start OSD 2

After this change the PG will refuse to start after the last step.

src/osd_peering.cpp

@@ -37,6 +37,10 @@ void osd_t::handle_peers()
                     still = true;
                 }
             }
+            else if (p.second.state & PG_PEERED)
+            {
+                still = true;
+            }
         }
         if (!still)
         {
@@ -57,6 +61,10 @@ void osd_t::handle_peers()
                 }
                 still = true;
             }
+            else if (p.second.state & PG_PEERED)
+            {
+                still = true;
+            }
         }
         if (!still)
         {
@@ -79,7 +87,7 @@ void osd_t::repeer_pgs(osd_num_t peer_osd)
     {
         auto & pg = p.second;
         bool repeer = false;
-        if (pg.state & (PG_PEERING | PG_ACTIVE | PG_INCOMPLETE))
+        if (pg.state & (PG_PEERING | PG_PEERED | PG_ACTIVE | PG_INCOMPLETE))
         {
             for (osd_num_t pg_osd: pg.all_peers)
             {