Enforce maximum char_length of UTF-8 data (Bug #10409).
Pad UTF-8 variable-length CHAR columns with 0x20.
Pad UCS2 CHAR columns with 0x0020 (Bug #10511).


innobase/data/data0type.c:
  dtype_get_at_most_n_mbchars(): Avoid division by zero in assertion
  when this function is called with dtype->mbmaxlen==0
innobase/row/row0ins.c:
  row_ins_cascade_calc_update_vec(): Enforce maximum char_length of
  UTF-8 data (Bug #10409).
  Pad UTF-8 CHAR columns with 0x20.
  Pad UCS2 CHAR columns with 0x0020 (Bug #10511).