Related to operator precedence and associativity.
Make the expressions as explicit as possible.

sql/field.h:
  Silence gcc-4.3 warning: be more explicit.
sql/item.cc:
  Silence gcc-4.3 warning: be more explicit.
sql/item_sum.cc:
  Silence gcc-4.3 warning: be more explicit.
sql/log_event.cc:
  Silence gcc-4.3 warning: be more explicit.
sql/spatial.h:
  Silence gcc-4.3 warning: be more explicit.
sql/sql_lex.cc:
  Silence gcc-4.3 warning: be more explicit.
sql/table.h:
  Silence gcc-4.3 warning: be more explicit.
storage/federated/ha_federated.cc:
  Fix operator precedence bug.
storage/heap/ha_heap.cc:
  Silence gcc-4.3 warning: be more explicit.