Fixes for valgrind errors and compatiblity issues by Monty


myisam/rt_split.c:
  Fixes for valgrind errors and compatiblity issues by Monty
sql/field_conv.cc:
  Fixes for valgrind errors and compatiblity issues by Monty
sql/sql_delete.cc:
  Fixes for valgrind errors and compatiblity issues by Monty
sql/sql_select.cc:
  Fixes for valgrind errors and compatiblity issues by Monty
strings/my_vsnprintf.c:
  Fixes for valgrind errors and compatiblity issues by Monty