Merge #19333: refactor: Fix clang compile failure

fa3b35a ci: Add test for clang-3.8 C++11 support (MarcoFalke)
faa7431 refactor: Fix clang compile failure (MarcoFalke)

Pull request description:

  Fix

  ```
  script/standard.cpp:278:22: error: default initialization of an object of const type 'const (anonymous namespace)::CScriptVisitor' without a user-provided default constructor
  const CScriptVisitor g_script_visitor;
                       ^
                                       {}
  1 error generated.

ACKs for top commit:
  laanwj:
    ACK fa3b35a

Tree-SHA512: b3251208945b44530224aadbc10fef1260b479c0b43a5e345501fbfd3579a9fe354b946090e023232852bbb99759da4429b58b137b7b286ddac6bd7960851f7f

Author: laanwj

ci/test/00_setup_env_native_nowallet.sh

@@ -8,7 +8,7 @@ export LC_ALL=C.UTF-8
 
 export CONTAINER_NAME=ci_native_nowallet
 export DOCKER_NAME_TAG=ubuntu:16.04  # Use xenial to have one config run the tests in python3.5, see doc/dependencies.md
-export PACKAGES="python3-zmq"
+export PACKAGES="python3-zmq clang-3.8 llvm-3.8"  # Use clang-3.8 to test C++11 compatibility, see doc/dependencies.md
 export DEP_OPTS="NO_WALLET=1"
 export GOAL="install"
-export BITCOIN_CONFIG="--enable-glibc-back-compat --enable-reduce-exports"
+export BITCOIN_CONFIG="--enable-glibc-back-compat --enable-reduce-exports CC=clang-3.8 CXX=clang++-3.8"

src/script/standard.cpp

@@ -290,14 +290,11 @@ class CScriptVisitor : public boost::static_visitor<CScript>
         return CScript() << CScript::EncodeOP_N(id.version) << std::vector<unsigned char>(id.program, id.program + id.length);
     }
 };
-
-const CScriptVisitor g_script_visitor;
-
 } // namespace
 
 CScript GetScriptForDestination(const CTxDestination& dest)
 {
-    return boost::apply_visitor(::g_script_visitor, dest);
+    return boost::apply_visitor(CScriptVisitor{}, dest);
 }
 
 CScript GetScriptForRawPubKey(const CPubKey& pubKey)