[DebugInfo] Stop emitting spare bits mask in debug info

We're now able to calculate the spare bits mask from other information.
Stop emitting it in debug info.

Author: augusto2112

lib/IRGen/IRGenDebugInfo.cpp

@@ -1389,21 +1389,9 @@ createSpecializedStructOrClassType(NominalOrBoundGenericNominalType *Type,
       }
     }
 
-    APInt SpareBitsMask;
-    auto &EnumStrategy =
-        getEnumImplStrategy(IGM, DbgTy.getType()->getCanonicalType());
-
-    auto VariantOffsetInBits = 0;
-    if (auto SpareBitsMaskInfo = EnumStrategy.calculateSpareBitsMask()) {
-      SpareBitsMask = SpareBitsMaskInfo->bits;
-      // The offset of the variant mask in the overall enum.
-      VariantOffsetInBits = SpareBitsMaskInfo->byteOffset * 8;
-    }
-
     auto VPTy = DBuilder.createVariantPart(
         Scope, {}, File, Line, SizeInBits, AlignInBits, Flags, nullptr,
-        DBuilder.getOrCreateArray(Elements), /*UniqueIdentifier=*/"",
-        VariantOffsetInBits, SpareBitsMask);
+        DBuilder.getOrCreateArray(Elements), /*UniqueIdentifier=*/"");
 
     auto DITy = DBuilder.createStructType(
         Scope, Name, File, Line, SizeInBits, AlignInBits, Flags, nullptr,