[corlib] Fix exposed public APIs

mcs/class/corlib/System.Diagnostics/StackTrace.cs

@@ -251,7 +251,7 @@ namespace System.Diagnostics {
 			return i != 0;
 		}
 
-		public static void GetFullNameForStackTrace (StringBuilder sb, MethodBase mi)
+		internal void GetFullNameForStackTrace (StringBuilder sb, MethodBase mi)
 		{
 			var declaringType = mi.DeclaringType;
 			if (declaringType.IsGenericType && !declaringType.IsGenericTypeDefinition)

mcs/class/corlib/System.Globalization/CultureInfo.cs

@@ -127,22 +127,18 @@ namespace System.Globalization
 			get {
 				return Thread.CurrentThread.CurrentCulture;
 			}
-#if NETSTANDARD
 			set {
 				throw new NotImplementedException ();
 			}
-#endif
 		}
 
 		public static CultureInfo CurrentUICulture { 
 			get {
 				return Thread.CurrentThread.CurrentUICulture;
 			}
-#if NETSTANDARD
 			set {
 				throw new NotImplementedException ();
 			}
-#endif
 		}
 
 		internal static CultureInfo ConstructCurrentCulture ()

mcs/class/corlib/System.Reflection/AssemblyName.cs

@@ -446,11 +446,9 @@ namespace System.Reflection {
 			get {
 				return (cultureinfo == null)? null : cultureinfo.Name;
 			}
-#if NETSTANDARD
 			set {
 				throw new NotImplementedException ();
 			}
-#endif
 		}
 
 		[ComVisibleAttribute(false)]