Do not access esi segment_id from segment being erased

boost::ptr_map::erase() API takes key argument by reference. Hence, by passing
segment->esi() as a reference to erase(), this key can be still accessed within
the boost container code while the segment that contains the key gets destroyed

Also fix a minor minor leak in bgp_evpn_aliasing_test.cc using scoped_ptr.

Change-Id: I2045699e103546a5fe3aef679b45c2a373326475
Closes-Bug: 1735558

src/bgp/bgp_evpn.cc

@@ -1043,7 +1043,8 @@ bool EvpnManager::ProcessSegmentDeleteSet() {
     BOOST_FOREACH(EvpnSegment *segment, segment_delete_set_) {
         if (segment->MayDelete()) {
             segment_update_set_.erase(segment);
-            segment_map_.erase(segment->esi());
+            EthernetSegmentId esi = segment->esi();
+            segment_map_.erase(esi);
         }
     }
     segment_delete_set_.clear();

src/bgp/test/bgp_evpn_aliasing_test.cc

@@ -147,7 +147,8 @@ class BgpEvpnAliasingTest : public ::testing::Test {
         blue_ = static_cast<EvpnTable *>(db->FindTable("blue.evpn.0"));
         blue_manager_ = blue_->GetEvpnManager();
         RibExportPolicy policy(BgpProto::XMPP, RibExportPolicy::XMPP, 0, 0);
-        blue_ribout_ = blue_->RibOutLocate(server_->update_sender(), policy);
+        blue_ribout_.reset(
+            blue_->RibOutLocate(server_->update_sender(), policy));
 
         CreateAllPeers();
 
@@ -462,7 +463,7 @@ class BgpEvpnAliasingTest : public ::testing::Test {
     EvpnTable *blue_;
     EvpnTable *master_;
     EvpnManager *blue_manager_;
-    RibOut *blue_ribout_;
+    boost::scoped_ptr<RibOut> blue_ribout_;
     vector<PeerMock *> bgp_peers_;
     EthernetSegmentId esi_null_, esi1_, esi2_, esi3_;
 };