(res_null_text): New static const struct res_id object,
with empty unicode name field.
(control): Pop parsing of optresidc up one level. Set
res_text_field to $2 except for controls which do not accept
a text field. Set res_text_field to res_null_text for the
special cases (viz. COMBOBOX, EDITTEXT, LISTBOX, SCROLLBAR).
(control_params): Adjust to use res_text_field rather
than optresidc.
(COMBOBOX): Add comment about discrepency between documented
vs. observed default style.
* resrc.c (define_control): Make first param const.
* windres.h (define_control): Adjust prototype.
testsuite:
* binutils-all/windres/checkbox.rc: New file.
* binutils-all/windres/checkbox.rsd: New file.
* binutils-all/windres/combobox.rc: New file.
* binutils-all/windres/combobox.rsd: New file.
* binutils-all/windres/edittext.rc: New file.
* binutils-all/windres/edittext.rsd: New file.
* binutils-all/windres/listbox.rc: New file.
* binutils-all/windres/listbox.rsd: New file.
* binutils-all/windres/scrollbar.rc: New file.
* binutils-all/windres/scrollbar.rsd: New file.
