absolute value of the float is less than 1, and also fix calculation of
length for negative values. (Bug #7774)


sql/field.cc:
  Fix handling of negative values and fabs(values> < 1 in Field_str::store
mysql-test/r/type_float.result:
  Add results
mysql-test/r/type_float.result.es:
  Add results
mysql-test/t/type_float.test:
  Add test for conversion of floats to character field