support extracting inlined public keys

Technically, the caller can do this but this is more convenient.

package.json

@@ -27,9 +27,9 @@
     },
     {
       "author": "whyrusleeping",
-      "hash": "QmaPbCnUMBohSGo3KnxEa2bHqyJVVeEEcwtqJAYxerieBo",
+      "hash": "Qme1knMqwt1hKZbc1BmQFmnm9f36nyQGwXxPGVpVJ9rMK5",
       "name": "go-libp2p-crypto",
-      "version": "1.5.0"
+      "version": "1.6.2"
     },
     {
       "author": "jbenet",
@@ -45,9 +45,9 @@
     },
     {
       "author": "whyrusleeping",
-      "hash": "QmZoWKhxUmZ2seW4BzX6fJkNR8hh9PsGModr7q171yq2SS",
+      "hash": "QmWxGnWZcUNVtpMk8jjX13pK1WT9jJnKQtEfvkGdxSMVRu",
       "name": "go-libp2p-peer",
-      "version": "2.2.3"
+      "version": "2.3.1"
     },
     {
       "author": "multiformats",

peerstore.go

@@ -127,6 +127,15 @@ func (kb *keybook) PubKey(p peer.ID) ic.PubKey {
 	kb.RLock()
 	pk := kb.pks[p]
 	kb.RUnlock()
+	if pk != nil {
+		return pk
+	}
+	pk, err := p.ExtractPublicKey()
+	if err == nil && pk != nil {
+		kb.Lock()
+		kb.pks[p] = pk
+		kb.Unlock()
+	}
 	return pk
 }