Fix a build break by adding a parameter to an otherwise parameterless struct ctor

src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs

@@ -1375,7 +1375,7 @@ private BoundStatement ChainImplicitStructConstructor(MethodSymbol methodSymbol,
                     while (index >= hoistedVariables.Count)
                     {
                         // Empty slots may be present if variables were deleted during EnC.
-                        hoistedVariables.Add(new EncHoistedLocalInfo());
+                        hoistedVariables.Add(new EncHoistedLocalInfo(true));
                     }
 
                     hoistedVariables[index] = new EncHoistedLocalInfo(field.SlotDebugInfo, (Cci.ITypeReference)field.Type);

src/Compilers/Core/Portable/Emit/EditAndContinue/EncHoistedLocalInfo.cs

@@ -13,7 +13,7 @@ internal struct EncHoistedLocalInfo : IEquatable<EncHoistedLocalInfo>
         public readonly LocalSlotDebugInfo SlotInfo;
         public readonly Cci.ITypeReference Type;
 
-        public EncHoistedLocalInfo()
+        public EncHoistedLocalInfo(bool ignored)
         {
             SlotInfo = new LocalSlotDebugInfo(SynthesizedLocalKind.EmitterTemp, LocalDebugId.None);
             Type = null;