BUG#12818224: 61921: WRITETRAXINBINLOG SHOULD BE WRITETRANXINBINLOG

IN SEMISYNC_MASTER.CC 

Fixing typo: writeTraxInBinlog() => writeTranxInBinlog() .

Additionally, fixed identation.

plugin/semisync/semisync_master.cc

@@ -316,7 +316,7 @@ int ActiveTranx::clear_active_tranx_nodes(const char *log_file_name,
  *                          the slave's status information.
  *  . updateSyncHeader():   based on transaction waiting information, decide
  *                          whether to request the slave to reply.
- *  . writeTraxInBinlog(): called by the transaction thread when it finishes
+ *  . writeTranxInBinlog(): called by the transaction thread when it finishes
  *                          writing all transaction events in binlog.
  *  . commitTrx():          transaction thread wait for the slave reply.
  *