Move LEX methods and related functions from sql_yacc.yy to sql_lex.cc

int LEX::case_stmt_action_expr(Item* expr);

int LEX::case_stmt_action_when(Item *when, bool simple);

int LEX::case_stmt_action_then();

bool LEX::set_system_variable(enum enum_var_type var_type,

                              sys_var *sysvar,

                              const Lex_ident_sys_st *base_name,

                              Item *val);

bool LEX::set_trigger_new_row(const LEX_CSTRING *name, Item *val)

Item_splocal *LEX::create_item_for_sp_var(const Lex_ident_cli_st *cname,

                                          sp_variable *spvar);

Item* handle_sql2003_note184_exception(THD *thd, Item* left, bool equal,

                                       Item *expr)

bool sp_create_assignment_lex(THD *thd, const char *pos)

bool sp_create_assignment_instr(THD *thd, bool no_lookahead,

                                bool need_set_keyword)

void LEX::add_key_to_list(LEX_CSTRING *field_name,

                          enum Key::Keytype type, bool check_exists)

bool LEX::add_alter_list(const char *name, Virtual_column_info *expr,

                         bool exists)

void LEX::init_last_field(Column_definition *field,

                          const LEX_CSTRING *field_name,

                          const CHARSET_INFO *cs)

bool LEX::set_bincmp(CHARSET_INFO *cs, bool bin)

Virtual_column_info *add_virtual_expression(THD *thd, Item *expr);