scripted-diff: Use the C++11 keyword nullptr to denote the pointer literal instead of the macro NULL

-BEGIN VERIFY SCRIPT-
sed -i 's/\<NULL\>/nullptr/g' src/*.cpp src/*.h src/*/*.cpp src/*/*.h src/qt/*/*.cpp src/qt/*/*.h src/wallet/*/*.cpp src/wallet/*/*.h src/support/allocators/*.h
sed -i 's/Prefer nullptr, otherwise SAFECOOKIE./Prefer NULL, otherwise SAFECOOKIE./g' src/torcontrol.cpp
sed -i 's/tor: Using nullptr authentication/tor: Using NULL authentication/g' src/torcontrol.cpp
sed -i 's/METHODS=nullptr/METHODS=NULL/g' src/test/torcontrol_tests.cpp src/torcontrol.cpp
sed -i 's/nullptr certificates/NULL certificates/g' src/qt/paymentserver.cpp
sed -i 's/"nullptr"/"NULL"/g' src/torcontrol.cpp src/test/torcontrol_tests.cpp
-END VERIFY SCRIPT-

src/core_write.cpp

@@ -92,7 +92,7 @@ std::string ScriptToAsmStr(const CScript& script, const bool fAttemptSighashDeco
                     // this won't decode correctly formatted public keys in Pubkey or Multisig scripts due to
                     // the restrictions on the pubkey formats (see IsCompressedOrUncompressedPubKey) being incongruous with the
                     // checks in CheckSignatureEncoding.
-                    if (CheckSignatureEncoding(vch, SCRIPT_VERIFY_STRICTENC, NULL)) {
+                    if (CheckSignatureEncoding(vch, SCRIPT_VERIFY_STRICTENC, nullptr)) {
                         const unsigned char chSigHashType = vch.back();
                         if (mapSigHashTypes.count(chSigHashType)) {
                             strSigHashDecode = "[" + mapSigHashTypes.find(chSigHashType)->second + "]";