Fixed connect.grant failure.

sql/create_options.cc:
  Keep "first" list intact, allocate new list for merge result.
  
  Normally "first" is options list on TABLE_SHARE. ALTER TABLE may fail
  after the merge and leave share with corrupt list in the table definition
  cache.
sql/create_options.h:
  Construct engine_option_value from another engine_option_value.