getTZKeyName in common/wintz.cpp leaks registry handle.

https://ssl.icu-project.org/trac/ticket/12908

diff --git a/intl/icu/source/common/wintz.c b/intl/icu/source/common/wintz.c
--- a/intl/icu/source/common/wintz.c
+++ b/intl/icu/source/common/wintz.c
@@ -211,16 +211,18 @@ static LONG getTZKeyName(char* tzKeyName
              hkey,
              "TimeZoneKeyName",
              NULL,
              NULL,
              (LPBYTE)tzKeyName,
              &cbData);
     }
 
+    RegCloseKey(hkey);
+
     return result;
 }
 
 /*
   This code attempts to detect the Windows time zone, as set in the
   Windows Date and Time control panel.  It attempts to work on
   multiple flavors of Windows (9x, Me, NT, 2000, XP) and on localized
   installs.  It works by directly interrogating the registry and