Use bool for boolean in textprop.c, undo.c

Use bool for boolean in textprop.c, undo.c

* src/textprop.c (soft, hard): Now constants instead of macros.
(validate_plist): Rewrite to avoid need for boolean local.
(interval_has_all_properties, interval_has_some_properties)
(interval_has_some_properties_list, add_properties)
(remove_properties, get_char_property_and_overlay)
(Fnext_single_char_property_change)
(Fprevious_single_char_property_change, add_text_properties_1)
(Fremove_text_properties, Fremove_list_of_text_properties)
(copy_text_properties):
* src/tparam.c (tparam1):
* src/undo.c (record_change, record_property_change)
(syms_of_undo):
Use 'true' and 'false' for booleans.