Make debugLog() return a beast::Journal (RIPD-1209):

Previously, writes using debugLog() tagged every entry with
"TRC:".  Now users of debugLog() must specify the severity
level they want their information logged at.

src/ripple/protocol/impl/STValidation.cpp

@@ -35,7 +35,7 @@ STValidation::STValidation (SerialIter& sit, bool checkSignature)
 
     if  (checkSignature && !isValid ())
     {
-        JLOG (debugLog())
+        JLOG (debugLog().error())
             << "Invalid validation" << getJson (0);
         Throw<std::runtime_error> ("Invalid validation");
     }
@@ -113,7 +113,7 @@ bool STValidation::isValid (uint256 const& signingHash) const
     }
     catch (std::exception const&)
     {
-        JLOG (debugLog())
+        JLOG (debugLog().error())
             << "Exception validating validation";
         return false;
     }