Inserting Data.

The problem was that under some circumstances Field class was not
properly initialized before calling create_length_to_internal_length()
function, which led to assert failure.

The fix is to do the proper initialization.

The user-visible problem was that under some circumstances
CREATE TABLE ... SELECT statement crashed the server or led
to wrong error message (wrong results).


mysql-test/r/select.result:
  Update result file.
mysql-test/t/select.test:
  Add a test case for BUG#30736: Row Size Too Large Error
  Creating a Table and Inserting Data.
sql/sql_table.cc:
  Move sql_field->decimals initialization before
  sql_field->create_length_to_internal_length() call.