Fix a minor mismatch between input arg, buffer passed

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/core/json/UTF8JsonGenerator.java

@@ -455,7 +455,7 @@ private void _writeLongString(char[] text, int offset, int len) throws IOExcepti
             _flushBuffer();
         }
         _outputBuffer[_outputTail++] = BYTE_QUOTE;
-        _writeStringSegments(_charBuffer, 0, len);
+        _writeStringSegments(text, 0, len);
         if (_outputTail >= _outputEnd) {
             _flushBuffer();
         }