scripted-diff: Avoid temporary copies when looping over std::map

The ::value_type of the std::map/std::multimap/std::unordered_map containers is
std::pair<const Key, T>. Dropping the const results in an unnecessary copy,
for example in C++11 range-based loops.

For this I started with a more general scripted diff, then narrowed it down
based on the inspection showing that all actual map/multimap/unordered_map
variables used in loops start with m or have map in the name.

-BEGIN VERIFY SCRIPT-
sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : m/for (\1std::pair<const \2\3 : m/' src/*.cpp src/**/*.cpp
sed -i -E 's/for \(([^<]*)std::pair<([^c])(.+) : (.*)map/for (\1std::pair<const \2\3 : \4map/' src/*.cpp src/**/*.cpp
-END VERIFY SCRIPT-

src/rpc/net.cpp

@@ -475,7 +475,7 @@ static UniValue getnetworkinfo(const JSONRPCRequest& request)
     UniValue localAddresses(UniValue::VARR);
     {
         LOCK(cs_mapLocalHost);
-        for (const std::pair<CNetAddr, LocalServiceInfo> &item : mapLocalHost)
+        for (const std::pair<const CNetAddr, LocalServiceInfo> &item : mapLocalHost)
         {
             UniValue rec(UniValue::VOBJ);
             rec.pushKV("address", item.first.ToString());