When executing ALTER TABLE all the attributes of the view were overwritten.
  This is contrary to the user's expectations.
  So some of the view attributes are preserved now : namely security and 
  algorithm. This means that if they are not specified in ALTER VIEW
  their values are preserved from CREATE VIEW instead of being defaulted.


mysql-test/r/view.result:
  Bug #21080: ALTER VIEW makes user restate SQL SECURITY mode, and ALGORITHM
   - test suite
mysql-test/t/view.test:
  Bug #21080: ALTER VIEW makes user restate SQL SECURITY mode, and ALGORITHM
   - test suite
sql/sql_lex.h:
  Bug #21080: ALTER VIEW makes user restate SQL SECURITY mode, and ALGORITHM
   - must make create_view_suid a tristate : on/off/unspecified
sql/sql_view.cc:
  Bug #21080: ALTER VIEW makes user restate SQL SECURITY mode, and ALGORITHM
   - open the view to get it's attributes and put then as defaults 
     for ALTER VIEW
sql/sql_yacc.yy:
  Bug #21080: ALTER VIEW makes user restate SQL SECURITY mode, and ALGORITHM
   - must make create_view_suid a tristate : on/off/unspecified
sql/table.h:
  Bug #21080: ALTER VIEW makes user restate SQL SECURITY mode, and ALGORITHM
   - must make create_view_suid a tristate : on/off/unspecified