Remove dependency on System.Security.Permissions package for .NET Standard and .NET Core

System.Security.Permissions package is used to check that ReflectionPermission
is granted to perform a small optimization for DynamicMethod, however in
.NET Standard and .NET Core permissions are not really supported and
SecurityManager.IsGranted always returns false.

Also for .NET Framework the obsoleted SecurityManager.IsGranted was replaced
with a preferred method of checking permissions.

Author: hazzik

src/NHibernate/Bytecode/Lightweight/ReflectionOptimizer.cs

@@ -101,13 +101,22 @@ protected virtual void ThrowExceptionForNoDefaultCtor(System.Type type)
 
 		protected DynamicMethod CreateDynamicMethod(System.Type returnType, System.Type[] argumentTypes)
 		{
-			System.Type owner = mappedType.IsInterface ? typeof (object) : mappedType;
-#pragma warning disable 612,618
-			bool canSkipChecks = SecurityManager.IsGranted(new ReflectionPermission(ReflectionPermissionFlag.MemberAccess));
-#pragma warning restore 612,618
+			var owner = mappedType.IsInterface ? typeof (object) : mappedType;
+			var canSkipChecks = CanSkipVisibilityChecks();
 			return new DynamicMethod(string.Empty, returnType, argumentTypes, owner, canSkipChecks);
 		}
 
+		private static bool CanSkipVisibilityChecks()
+		{
+#if NETFX
+			var permissionSet = new PermissionSet(PermissionState.None);
+			permissionSet.AddPermission(new ReflectionPermission(ReflectionPermissionFlag.MemberAccess));
+			return permissionSet.IsSubsetOf(AppDomain.CurrentDomain.PermissionSet);
+#else
+			return false;
+#endif
+		}
+
 		private static void EmitCastToReference(ILGenerator il, System.Type type)
 		{
 			if (type.IsValueType)

src/NHibernate/Driver/OdbcDriver.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Common;
-using System.Data.Odbc;
 using NHibernate.SqlTypes;
 using NHibernate.Util;
 using Environment = NHibernate.Cfg.Environment;
@@ -47,12 +46,12 @@ public OdbcDriver()
 #else
 		public override DbConnection CreateConnection()
 		{
-			return new OdbcConnection();
+			return new System.Data.Odbc.OdbcConnection();
 		}
 
 		public override DbCommand CreateCommand()
 		{
-			return new OdbcCommand();
+			return new System.Data.Odbc.OdbcCommand();
 		}
 #endif
 

src/NHibernate/Driver/OleDbDriver.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Data.Common;
-using System.Data.OleDb;
 
 namespace NHibernate.Driver
 {
@@ -26,12 +25,12 @@ public OleDbDriver()
 #else
 		public override DbConnection CreateConnection()
 		{
-			return new OleDbConnection();
+			return new System.Data.OleDb.OleDbConnection();
 		}
 
 		public override DbCommand CreateCommand()
 		{
-			return new OleDbCommand();
+			return new System.Data.OleDb.OleDbCommand();
 		}
 #endif
 

src/NHibernate/NHibernate.csproj

@@ -53,12 +53,10 @@
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp2.0'">
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="4.4.1" />
-    <PackageReference Include="System.Security.Permissions" Version="4.4.1" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="4.4.1" />
-    <PackageReference Include="System.Security.Permissions" Version="4.4.1" />
     <PackageReference Include="System.Reflection.Emit" Version="4.3.0" />
     <PackageReference Include="System.Reflection.Emit.Lightweight" Version="4.3.0" />
   </ItemGroup>