Cherry pick an upstream cl for host tz detection

source/test/intltest/tztest.cpp

 /***********************************************************************
  * COPYRIGHT: 
  * Copyright (c) 1997-2014, International Business Machines Corporation
  * and others. All Rights Reserved.
  ***********************************************************************/
 
 #include "unicode/utypes.h"
 
 #if !UCONFIG_NO_FORMATTING
 
@@ skipping 117 matching lines @@
         /*
          * Ticket#6364 and #7648
          * A few time zones are using GMT offests not a multiple of 15 minutes.
          * Therefore, we should not interpret such case as an error.
          * We downgrade this from errln to infoln. When we see this message,
          * we should examine if it is ignorable or not.
          */
         infoln("WARNING: t_timezone may be incorrect. It is not a multiple of 15min.", tzoffset);
     }
 
+    TimeZone* hostZone = TimeZone::detectHostTimeZone();
+    /* Host time zone's offset should match the offset returned by uprv_timezone() */
+    if (hostZone->getRawOffset() != tzoffset * (-1000)) {
+        errln("FAIL: detectHostTimeZone()'s raw offset != host timezone's offset");
+    }
+    delete hostZone;
+
     UErrorCode status = U_ZERO_ERROR;
     const char* tzver = TimeZone::getTZDataVersion(status);
     if (U_FAILURE(status)) {
         errcheckln(status, "FAIL: getTZDataVersion failed - %s", u_errorName(status));
     } else if (uprv_strlen(tzver) != 5 /* 4 digits + 1 letter */) {
         errln((UnicodeString)"FAIL: getTZDataVersion returned " + tzver);
     } else {
         logln((UnicodeString)"tzdata version: " + tzver);
     }
 }
@@ skipping 2269 matching lines @@
         UnicodeString id;
 
         TimeZone::getIDForWindowsID(UnicodeString(TESTDATA[i].winid), TESTDATA[i].region,
                                     id, sts);
         assertSuccess(UnicodeString(TESTDATA[i].winid) + "/" + TESTDATA[i].region, sts);
         assertEquals(UnicodeString(TESTDATA[i].winid) + "/" + TESTDATA[i].region, TESTDATA[i].id, id, TRUE);
     }
 }
 
 #endif /* #if !UCONFIG_NO_FORMATTING */