[flang] fold LOGICAL intrinsic calls

[jeanPerier]

Summary

Folding of LOGICAL intrinsic procedure was missing in the front-end causing
crash when using it in parameter expressions.
Simply fold LOGICAL calls to evaluate::Convert<T>.

[PeteSteinfeld]

All builds, tests, and looks good.

flang/lib/Evaluate/fold-logical.cpp

Expr<Type<TypeCategory::Logical, KIND>> FoldIntrinsicFunction(
   } else if (name == "is_contiguous") {
     if (args.at(0)) {
       if (auto *expr{args[0]->UnwrapExpr()}) {
         if (IsSimplyContiguous(*expr, context)) {
           return Expr<T>{true};
         }
       }
     }
+  } else if (name == "logical") {
+    if (auto *expr{UnwrapExpr<Expr<SomeLogical>>(args[0])}) {
+      return Fold(context, ConvertToType<T>(std::move(*expr)));
+    }
   } else if (name == "merge") {
     return FoldMerge<T>(context, std::move(funcRef));
   } else if (name == "__builtin_ieee_support_datatype" ||
       name == "__builtin_ieee_support_denormal" ||
       name == "__builtin_ieee_support_divide" ||
       name == "__builtin_ieee_support_divide" ||
       name == "__builtin_ieee_support_inf" ||
       name == "__builtin_ieee_support_io" ||

flang/test/Evaluate/folding01.f90

! Check logical intrinsic operation folding
   logical, parameter :: test_eqv3 = .NOT.(.false..EQV..true.)
   logical, parameter :: test_eqv4 = .NOT.(.true..EQV..false.)
 
   logical, parameter :: test_neqv1 = .true..NEQV..false.
   logical, parameter :: test_neqv2 = .false..NEQV..true.
   logical, parameter :: test_neqv3 = .NOT.(.false..NEQV..false.)
   logical, parameter :: test_neqv4 = .NOT.(.true..NEQV..true.)
 
+  logical, parameter :: test_logical1 = logical(logical(.true., 2))
+  logical, parameter :: test_logical2 = .NOT.logical(logical(.false., 2))
+
 ! Check integer intrinsic operator folding
 
 ! Check integer relational intrinsic operation folding
   logical, parameter :: test_le_i1 = 1.LE.2
   logical, parameter :: test_le_i2 = .NOT.(2.LE.1)
   logical, parameter :: test_le_i3 = 2.LE.2
   logical, parameter :: test_le_i4 = -1.LE.2
   logical, parameter :: test_le_i5 = .NOT.(-2.LE.-3)