Reorder checks so the 1st looks less special-casey

 * As the previous commit showed, the `IsGenericParameter` check must
   have priority... probably not just over enums, but over any other
   value types, too.

 * The `IsEnum` check can be put behind `IsValueType` so it does not run
   for non-value types.

src/Castle.Core/DynamicProxy/Generators/Emitters/OpCodeUtil.cs

@@ -27,12 +27,6 @@ internal abstract class OpCodeUtil
  /// </summary>
  public static void EmitLoadIndirectOpCodeForType(ILGenerator gen, Type type)
  {
- if (type.IsEnum && !type.IsGenericParameter)
- {
- EmitLoadIndirectOpCodeForType(gen, GetUnderlyingTypeOfEnum(type));
- return;
- }
-
  if (type.IsByRef)
  {
  throw new NotSupportedException("Cannot load ByRef values");
@@ -48,13 +42,20 @@ public static void EmitLoadIndirectOpCodeForType(ILGenerator gen, Type type)
 
  gen.Emit(opCode);
  }
- else if (type.IsValueType)
+ else if (type.IsGenericParameter)
  {
  gen.Emit(OpCodes.Ldobj, type);
  }
- else if (type.IsGenericParameter)
+ else if (type.IsValueType)
  {
- gen.Emit(OpCodes.Ldobj, type);
+ if (type.IsEnum)
+ {
+ EmitLoadIndirectOpCodeForType(gen, GetUnderlyingTypeOfEnum(type));
+ }
+ else
+ {
+ gen.Emit(OpCodes.Ldobj, type);
+ }
  }
  else
  {
@@ -107,12 +108,6 @@ public static void EmitLoadOpCodeForDefaultValueOfType(ILGenerator gen, Type typ
  /// </summary>
  public static void EmitStoreIndirectOpCodeForType(ILGenerator gen, Type type)
  {
- if (type.IsEnum && !type.IsGenericParameter)
- {
- EmitStoreIndirectOpCodeForType(gen, GetUnderlyingTypeOfEnum(type));
- return;
- }
-
  if (type.IsByRef)
  {
  throw new NotSupportedException("Cannot store ByRef values");
@@ -128,13 +123,20 @@ public static void EmitStoreIndirectOpCodeForType(ILGenerator gen, Type type)
 
  gen.Emit(opCode);
  }
- else if (type.IsValueType)
+ else if (type.IsGenericParameter)
  {
  gen.Emit(OpCodes.Stobj, type);
  }
- else if (type.IsGenericParameter)
+ else if (type.IsValueType)
  {
- gen.Emit(OpCodes.Stobj, type);
+ if (type.IsEnum)
+ {
+ EmitStoreIndirectOpCodeForType(gen, GetUnderlyingTypeOfEnum(type));
+ }
+ else
+ {
+ gen.Emit(OpCodes.Stobj, type);
+ }
  }
  else
  {