Fix typo in xlog.c.
Author: Fujii Masao
Discussion:
@@ -3184,7 +3184,7 @@ XLogNeedsFlush(XLogRecPtr record)
/*
* Create a new XLOG file segment, or open a pre-existing one.
*
- * log, seg: identify segment to be created/opened.
+ * logsegno: identify segment to be created/opened.
*
* *use_existent: if true, OK to use a pre-existing file (else, any
* pre-existing file will be deleted). On return, true if a pre-existing
