Fix SoftSetArg to also set value in mapMultiArgs

Without this fix, setting -bind=x on the CLI is different from
SoftSetArg("-bind", "x") in C++, which previously only set
the value in mapArgs

src/util.cpp

@@ -1,6 +1,6 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2014 The Bitcoin Core developers
-// Copyright (c) 2016-2024 The Hush developers
+// Copyright (c) 2016-2025 The Hush developers
 // Distributed under the GPLv3 software license, see the accompanying
 // file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html
 
@@ -438,6 +438,7 @@ bool SoftSetArg(const std::string& strArg, const std::string& strValue)
     if (mapArgs.count(strArg))
         return false;
     mapArgs[strArg] = strValue;
+    mapMultiArgs[strArg].push_back(strValue);
     return true;
 }