getinfo rpc needs a cs_wallet lock

Without it we get an AssertLockHeld when calling GetKeyPoolSize .
We could probably make this lock apply to less code, possibly only
the single line that calls GetKeyPoolSize() needs it.

src/rpc/misc.cpp

@@ -231,11 +231,12 @@ UniValue getinfo(const UniValue& params, bool fHelp, const CPubKey& mypk)
             + HelpExampleCli("getinfo", "")
             + HelpExampleRpc("getinfo", "")
         );
-    //#ifdef ENABLE_WALLET
+
-    //    LOCK2(cs_main, pwalletMain ? &pwalletMain->cs_wallet : NULL);
+#ifdef ENABLE_WALLET
-    //#else
+    LOCK2(cs_main, pwalletMain ? &pwalletMain->cs_wallet : NULL);
+#else
     LOCK(cs_main);
-    //#endif
+#endif
     
     proxyType proxy;
     GetProxy(NET_IPV4, proxy);