Fix bugs in foreach deconstruction and deconstruction declaration, if the same variable is used multiple times.

ICSharpCode.Decompiler/CSharp/StatementBuilder.cs

@@ -810,6 +810,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			var expectedType = deconstruction.Pattern.Variable.Type;
 			if (!NormalizeTypeVisitor.TypeErasure.EquivalentTypes(operandType, expectedType))
 				return false;
+			var usedVariables = new HashSet<ILVariable>(ILVariableEqualityComparer.Instance);
 			foreach (var item in deconstruction.Assignments.Instructions) {
 				if (!item.MatchStLoc(out var v, out var value))
 					return false;
@@ -822,6 +823,8 @@ namespace ICSharpCode.Decompiler.CSharp
 					return false;
 				if (!(v.CaptureScope == null || v.CaptureScope == usingContainer))
 					return false;
+				if (!usedVariables.Add(v))
+					return false;
 			}
 			return true;
 		}

ICSharpCode.Decompiler/CSharp/Transforms/DeclareVariables.cs

@@ -450,7 +450,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 				{
 					if (!inst.MatchStLoc(out var v, out var value))
 						return false;
-					if (!g.Any(vd => vd.ILVariable == v))
+					if (!g.Any(vd => vd.ILVariable == v && !vd.RemovedDueToCollision))
 						return false;
 					if (!usedVariables.Add(v))
 						return false;