Implement locale-sensitive string collation for MS-Windows. (Bug#18051)

Implement locale-sensitive string collation for MS-Windows.  (Bug#18051)

 src/w32proc.c (get_lcid_callback, get_lcid, w32_compare_strings):
 New functions.
 src/w32.h (w32_compare_strings): Add prototype.
 src/w32.c <g_b_init_compare_string_w>: New global flag.
 (globals_of_w32): Initialize it.
 src/sysdep.c (str_collate) [WINDOWSNT]: Implementation for MS-Windows.
 src/fns.c (Fstring_collate_lessp, Fstring_collate_equalp)
 [WINDOWSNT]: Call str_collate on MS-Windows.

 etc/NEWS: Mention that string-collate-* functions are supported on
 MS-Windows as well.