Mark value checking functions from before ad_page_contract as deprecated
(see also issue #3407)
A 16 years old comment says:
This is some old security crud from before we had ad_page_contract
check_for_form_variable_naughtiness
ad_var_type_check_integer_p
ad_var_type_check_safefilename_p
ad_var_type_check_dirname_p
ad_var_type_check_number_p
ad_var_type_check_word_p
ad_var_type_check_nocheck_p
ad_var_type_check_noquote_p
ad_var_type_check_integerlist_p