Fix ICU time zone support on iOS

source/common/putil.c

 /*
 ******************************************************************************
 *
 *   Copyright (C) 1997-2010, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 ******************************************************************************
 *
 *  FILE NAME : putil.c (previously putil.cpp and ptypes.cpp)
 *
@@ skipping 605 matching lines @@
 }
 
 U_CAPI int32_t U_EXPORT2
 uprv_timezone()
 {
 #ifdef U_TIMEZONE
     return U_TIMEZONE;
 #else
     time_t t, t1, t2;
     struct tm tmrec;
+#ifndef U_IOS
     UBool dst_checked;
+#endif
     int32_t tdiff = 0;
 
     time(&t);
     uprv_memcpy( &tmrec, localtime(&t), sizeof(tmrec) );
+#ifndef U_IOS
     dst_checked = (tmrec.tm_isdst != 0); /* daylight savings time is checked*/
+#endif
     t1 = mktime(&tmrec);                 /* local time in seconds*/
     uprv_memcpy( &tmrec, gmtime(&t), sizeof(tmrec) );
     t2 = mktime(&tmrec);                 /* GMT (or UTC) in seconds*/
     tdiff = t2 - t1;
+#ifndef U_IOS
+    /* On iOS the calculated tdiff is correct so and doesn't need this dst
+       shift applied. */
     /* imitate NT behaviour, which returns same timezone offset to GMT for
        winter and summer*/
     if (dst_checked)
         tdiff += 3600;
+#endif
     return tdiff;
 #endif
 }
 
 /* Note that U_TZNAME does *not* have to be tzname, but if it is,
    some platforms need to have it declared here. */
 
 #if defined(U_TZNAME) && (defined(U_IRIX) || defined(U_DARWIN) || defined(U_CYGWIN))
 /* RS6000 and others reject char **tzname.  */
 extern U_IMPORT char *U_TZNAME[];
 #endif
 
-#if !UCONFIG_NO_FILE_IO && (defined(U_DARWIN) || defined(U_LINUX) || defined(U_BSD))
+#if !UCONFIG_NO_FILE_IO && ((defined(U_DARWIN) && !defined(U_IOS)) || defined(U_LINUX) || defined(U_BSD))
 /* These platforms are likely to use Olson timezone IDs. */
 #define CHECK_LOCALTIME_LINK 1
 #if defined(U_DARWIN)
 #include <tzfile.h>
 #define TZZONEINFO      (TZDIR "/")
 #else
 #define TZDEFAULT       "/etc/localtime"
 #define TZZONEINFO      "/usr/share/zoneinfo/"
 #endif
 #if U_HAVE_DIRENT_H
@@ skipping 1570 matching lines @@
 #endif /* U_ENABLE_DYLOAD */
 
 /*
  * Hey, Emacs, please set the following:
  *
  * Local Variables:
  * indent-tabs-mode: nil
  * End:
  *
  */