Implement case-insensitive and Unicode-compliant collation on MS-Windows.

Implement case-insensitive and Unicode-compliant collation on MS-Windows.

 src/fns.c (Fstring_collate_lessp, Fstring_collate_equalp): Doc fix.
 src/w32proc.c (w32_compare_strings): Accept additional argument
 IGNORE_CASE.  Set up the flags for CompareStringW to ignore case
 if requested.  If w32-collate-ignore-punctuation is non-nil, add
 NORM_IGNORESYMBOLS to the flags.
 (LINGUISTIC_IGNORECASE): Define if not already defined.
 (syms_of_ntproc) <Vw32_collate_ignore_punctuation>: New variable.
 src/sysdep.c (str_collate) [WINDOWSNT]: Adapt to the interface
 change.
 src/w32.h: Adjust prototype of w32_compare_strings.

 etc/NEWS: Mention w32-collate-ignore-punctuation.

Fixes: debbugs:18051