[newlib-cygwin] TZ: Replace unreliable isupper calls on wchars

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=030d86d04dbd6ae878ff894256c5a465890d5970

commit 030d86d04dbd6ae878ff894256c5a465890d5970
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Wed May 25 12:13:03 2016 +0200

    TZ: Replace unreliable isupper calls on wchars
    
    In case the TZ variable is empty, Cygwin fetches timezone info from
    Windows.  Extracting the timezone short name uses isupper on wide chars.
    Replace with explicit check for A <= character <= Z to be independent
    of undefined behaviour.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/localtime.cc | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/localtime.cc b/winsup/cygwin/localtime.cc
index d57a020..2d10508 100644
--- a/winsup/cygwin/localtime.cc
+++ b/winsup/cygwin/localtime.cc
@@ -1543,7 +1543,8 @@ tzsetwall (void)
 	    GetTimeZoneInformation(&tz);
 	    dst = cp = buf;
 	    for (src = tz.StandardName; *src; src++)
-	      if (isupper(*src)) *dst++ = *src;
+	      if (*src >= L'A' && *src <= L'Z')
+		*dst++ = *src;
 	    if ((dst - cp) < 3)
 	      {
 		/* In non-english Windows, converted tz.StandardName
@@ -1561,7 +1562,8 @@ tzsetwall (void)
 		cp = strchr(cp, 0);
 		dst = cp;
 		for (src = tz.DaylightName; *src; src++)
-		  if (isupper(*src)) *dst++ = *src;
+		  if (*src >= L'A' && *src <= L'Z')
+		    *dst++ = *src;
 		if ((dst - cp) < 3)
 		  {
 		    /* In non-english Windows, converted tz.DaylightName