client code and replication slave code, as far as LOAD DATA INFILE and
other queries' execution is concerned. Duplication of code leads to
replication bugs, because the replication duplicate lags much behind.
Fix for 2 Valgrind errors on slave replicating LOAD DATA INFILE
  - one serious (causing a random test failure in rpl_loaddata in 5.0)
  - one not serious (theoretically a bug but not dangerous): uninited thd->row_count