Fix mscorlib asmmeta and add SecurityCritical attribute to the two ne…

…w functions in AssemblyExtensions

[tfs-changeset: 1524637]

src/mscorlib/src/System/Reflection/Metadata/AssemblyExtensions.cs

@@ -10,6 +10,7 @@ namespace System.Reflection.Metadata
     public static class AssemblyExtensions
     {
         [DllImport(JitHelpers.QCall)]
+        [SecurityCritical] // unsafe method
         [SuppressUnmanagedCodeSecurity]
         [return: MarshalAs(UnmanagedType.Bool)]
         private unsafe static extern bool InternalTryGetRawMetadata(RuntimeAssembly assembly, ref byte* blob, ref int length);
@@ -22,6 +23,7 @@ public static class AssemblyExtensions
         //     associated, is alive. The caller is responsible for keeping the assembly object alive while accessing the
         //     metadata blob.
         [CLSCompliant(false)] // out byte* blob
+        [SecurityCritical] // unsafe method
         public unsafe static bool TryGetRawMetadata(this Assembly assembly, out byte* blob, out int length)
         {
             if (assembly == null)