Fix the tz detection code.

source/i18n/timezone.cpp

 /*
 *******************************************************************************
 * Copyright (C) 1997-2015, International Business Machines Corporation and
 * others. All Rights Reserved.
 *******************************************************************************
 *
 * File TIMEZONE.CPP
 *
 * Modification History:
 *
@@ skipping 435 matching lines @@
     // We access system timezone data through TPlatformUtilities,
     // including tzset(), timezone, and tzname[].
     int32_t rawOffset = 0;
     const char *hostID;
 
     // First, try to create a system timezone, based
     // on the string ID in tzname[0].
 
     uprv_tzset(); // Initialize tz... system data
 
+    uprv_tzname_clear_cache();
+
     // Get the timezone ID from the host.  This function should do
     // any required host-specific remapping; e.g., on Windows this
     // function maps the Date and Time control panel setting to an
     // ICU timezone ID.
     hostID = uprv_tzname(0);
 
     // Invert sign because UNIX semantics are backwards
     rawOffset = uprv_timezone() * -U_MILLIS_PER_SECOND;
 
     TimeZone* hostZone = NULL;
@@ skipping 1218 matching lines @@
     return id;
 }
 #endif /* U_HIDE_DRAFT_API */
 
 
 U_NAMESPACE_END
 
 #endif /* #if !UCONFIG_NO_FORMATTING */
 
 //eof