[trivial] Reuse translation and cleanup DEFAULT_* values

* DEFAULT_DISABLE_SAFEMODE = false
* Use DEFAULT_* constants for extern bools

src/script/standard.cpp

@@ -16,7 +16,7 @@ using namespace std;
 
 typedef vector<unsigned char> valtype;
 
-bool fAcceptDatacarrier = true;
+bool fAcceptDatacarrier = DEFAULT_ACCEPT_DATACARRIER;
 unsigned nMaxDatacarrierBytes = MAX_OP_RETURN_RELAY;
 
 CScriptID::CScriptID(const CScript& in) : uint160(Hash160(in.begin(), in.end())) {}