Cygwin: globify: read full 32 bit character

While commit 0321fb5736 ("Cygwin: glob: convert wchar_t to wint_t")
switched the entire glob mechanism from wchar_t to wint_t, the globify
function calling glob on a DOS command line did not catch up and only
checked for the next character constituting a 16 bit wchar_t. This
broke reading surrogate pairs from incoming DOS command lines if the
string had to go through glob(3).

Check for an entire 32 bit unicode char instead.

Fixes: 0321fb5736 ("Cygwin: glob: convert wchar_t to wint_t")
Reported-by: David Allsopp <david@tarides.com>
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/dcrt0.cc

@@ -236,12 +236,13 @@ globify (char *word, char **&argv, int &argc, int &argvlen)
 	char quote = *s;
 	while (*++s && *s != quote)
 	  {
+	    mbstate_t mbs = { 0 };
 	    if (dos_spec || *s != '\\')
 	      /* nothing */;
 	    else if (s[1] == quote || s[1] == '\\')
 	      s++;
 	    *p++ = '\\';
-	    size_t cnt = isascii (*s) ? 1 : mbtowc (NULL, s, MB_CUR_MAX);
+	    size_t cnt = isascii (*s) ? 1 : mbrtowi (NULL, s, MB_CUR_MAX, &mbs);
 	    if (cnt <= 1 || cnt == (size_t)-1)
 	      *p++ = *s;
 	    else

winsup/cygwin/release/3.5.4

@@ -4,3 +4,7 @@ Fixes:
 - Fix regression in 3.5.3 which fails to open files for stat(2) if the
   file is opened exclusively by another process.
   Addresses: https://cygwin.com/pipermail/cygwin/2024-April/255811.html
+
+- Fix regression introduced in 3.5.0 when reading surrogate pairs (i.e.,
+  unicode chars >= 0x10000) from the DOS command line.  Addresses:
+  https://cygwin.com/pipermail/cygwin/2024-April/255807.html