Return early in IsBanned.

I am not aware of any reason that we'd try to stop a ban-list timing
 side-channel and the prior code wouldn't be enough if we were.

src/net.cpp

@@ -469,35 +469,31 @@ void CConnman::ClearBanned()
 
 bool CConnman::IsBanned(CNetAddr ip)
 {
-    bool fResult = false;
-    {
     LOCK(cs_setBanned);
     for (banmap_t::iterator it = setBanned.begin(); it != setBanned.end(); it++)
     {
         CSubNet subNet = (*it).first;
         CBanEntry banEntry = (*it).second;
 
-            if(subNet.Match(ip) && GetTime() < banEntry.nBanUntil)
+        if (subNet.Match(ip) && GetTime() < banEntry.nBanUntil) {
-                fResult = true;
+            return true;
         }
     }
-    return fResult;
+    return false;
 }
 
 bool CConnman::IsBanned(CSubNet subnet)
 {
-    bool fResult = false;
-    {
     LOCK(cs_setBanned);
     banmap_t::iterator i = setBanned.find(subnet);
     if (i != setBanned.end())
     {
         CBanEntry banEntry = (*i).second;
-            if (GetTime() < banEntry.nBanUntil)
+        if (GetTime() < banEntry.nBanUntil) {
-                fResult = true;
+            return true;
         }
     }
-    return fResult;
+    return false;
 }
 
 void CConnman::Ban(const CNetAddr& addr, const BanReason &banReason, int64_t bantimeoffset, bool sinceUnixEpoch) {