net: remove useless call to IsReachable() from CConnman::Bind()

`CConnman::Bind()` is called without `BF_EXPLICIT` only when passed
either `0.0.0.0` or `::`. For those addresses `IsReachable()` is always
true (regardless of the `-onlynet=` setting!), meaning that the `if`
condition never evaluates to true.

`IsReachable()` is always true for the "any" IPv4 and IPv6 addresses
because `CNetAddr::GetNetwork()` returns `NET_UNROUTABLE` instead of
`NET_IPV4` or `NET_IPV6` and the network `NET_UNROUTABLE` is always
considered reachable.

It follows that `BF_EXPLICIT` is unnecessary, remove it too.

Author: vasild

src/net.cpp

@@ -91,13 +91,12 @@ static constexpr auto FEELER_SLEEP_WINDOW{1s};
 /** Used to pass flags to the Bind() function */
 enum BindFlags {
     BF_NONE         = 0,
-    BF_EXPLICIT     = (1U << 0),
-    BF_REPORT_ERROR = (1U << 1),
+    BF_REPORT_ERROR = (1U << 0),
     /**
      * Do not call AddLocal() for our special addresses, e.g., for incoming
      * Tor connections, to prevent gossiping them over the network.
      */
-    BF_DONT_ADVERTISE = (1U << 2),
+    BF_DONT_ADVERTISE = (1U << 1),
 };
 
 // The set of sockets cannot be modified while waiting
@@ -2204,9 +2203,6 @@ bool CConnman::Bind(const CService& addr_, unsigned int flags, NetPermissionFlag
 {
     const CService addr{MaybeFlipIPv6toCJDNS(addr_)};
 
-    if (!(flags & BF_EXPLICIT) && !IsReachable(addr)) {
-        return false;
-    }
     bilingual_str strError;
     if (!BindListenPort(addr, strError, permissions)) {
         if ((flags & BF_REPORT_ERROR) && m_client_interface) {
@@ -2226,13 +2222,13 @@ bool CConnman::InitBinds(const Options& options)
 {
     bool fBound = false;
     for (const auto& addrBind : options.vBinds) {
-        fBound |= Bind(addrBind, (BF_EXPLICIT | BF_REPORT_ERROR), NetPermissionFlags::None);
+        fBound |= Bind(addrBind, BF_REPORT_ERROR, NetPermissionFlags::None);
     }
     for (const auto& addrBind : options.vWhiteBinds) {
-        fBound |= Bind(addrBind.m_service, (BF_EXPLICIT | BF_REPORT_ERROR), addrBind.m_flags);
+        fBound |= Bind(addrBind.m_service, BF_REPORT_ERROR, addrBind.m_flags);
     }
     for (const auto& addr_bind : options.onion_binds) {
-        fBound |= Bind(addr_bind, BF_EXPLICIT | BF_DONT_ADVERTISE, NetPermissionFlags::None);
+        fBound |= Bind(addr_bind, BF_DONT_ADVERTISE, NetPermissionFlags::None);
     }
     if (options.bind_on_any) {
         struct in_addr inaddr_any;