[flang] Don't discard lower bounds of implicit-shape named constants

[klausler]

Summary

The compiler preserves lower bounds of explicit-shape named constant arrays, but
failed to also do so for implicit-shape named constants. Fix.

flang/lib/Evaluate/check-expression.cpp

if (!converted &&
       }
     }
     if (converted) {
       auto folded{Fold(context, std::move(*converted))};
       if (IsActuallyConstant(folded)) {
         int symRank{GetRank(symTS->shape())};
         if (IsImpliedShape(symbol)) {
           if (folded.Rank() == symRank) {
-            return {std::move(folded)};
+            return ArrayConstantBoundChanger{
+                std::move(*AsConstantExtents(
+                    context, GetRawLowerBounds(context, NamedEntity{symbol})))}
+                .ChangeLbounds(std::move(folded));
           } else {
             context.messages().Say(
                 "Implied-shape parameter '%s' has rank %d but its initializer has rank %d"_err_en_US,
                 symbol.name(), symRank, folded.Rank());
           }
         } else if (auto extents{AsConstantExtents(context, symTS->shape())}) {
           if (folded.Rank() == 0 && symRank == 0) {
             // symbol and constant are both scalars