Don't trim TimeZone names ending in parenthesys.

Such as "Central Standard Time (Mexico)"

(cherry picked from commit 33332da)

mcs/class/corlib/System/TimeZoneInfo.cs

@@ -288,7 +288,8 @@ private static string TrimSpecial (string str)
 			var Istart = 0;
 			while (Istart < str.Length && !char.IsLetterOrDigit(str[Istart])) Istart++;
 			var Iend = str.Length - 1;
-			while (Iend > Istart && !char.IsLetterOrDigit(str[Iend])) Iend--;
+			while (Iend > Istart && !char.IsLetterOrDigit(str[Iend]) && str[Iend] != ')') // zone name can include parentheses like "Central Standard Time (Mexico)"
+				Iend--;
 
 			return str.Substring (Istart, Iend-Istart+1);
 		}