Improved support for TimeZoneInfo under windows.

When cross compiling with gcc, LIBC is defined and
thus never checks the registry for the timezone information.

This change is released under the MIT license.

(cherry picked from commit b3eccc8)

mcs/class/System.Core/System/TimeZoneInfo.cs

@@ -116,7 +116,14 @@ static TimeZoneInfo CreateLocal ()
 			using (Stream stream = GetMonoTouchData (null)) {
 				return BuildFromStream ("Local", stream);
 			}
-#elif LIBC
+#else
+			if (IsWindows && LocalZoneKey != null) {
+				string name = (string)LocalZoneKey.GetValue ("TimeZoneKeyName");
+				name = TrimSpecial (name);
+				if (name != null)
+					return TimeZoneInfo.FindSystemTimeZoneById (name);
+			}
+
 			var tz = Environment.GetEnvironmentVariable ("TZ");
 			if (tz != null) {
 				if (tz == String.Empty)
@@ -137,15 +144,6 @@ static TimeZoneInfo CreateLocal ()
 					return null;
 				}
 			}
-#else
-			if (IsWindows && LocalZoneKey != null) {
-				string name = (string)LocalZoneKey.GetValue ("TimeZoneKeyName");
-				name = TrimSpecial (name);
-				if (name != null)
-					return TimeZoneInfo.FindSystemTimeZoneById (name);
-			}
-
-			return null;
 #endif
 		}