[flang] Correct TypeCode::IsLogical()

[klausler]

Summary

F18 is using the type codes for C's "least" int types to encode
the various kinds of Fortran's LOGICAL intrinsic type; update
the IsLogical() predicate accordingly. (This member function
isn't yet used anywhere, so this patch is nearly an NFC.)

[jeanPerier]

LGTM

flang/runtime/type-code.h

return raw_ >= CFI_type_float_Complex &&
         raw_ <= CFI_type_long_double_Complex;
   }
   constexpr bool IsCharacter() const {
     return raw_ == CFI_type_char || raw_ == CFI_type_char16_t ||
         raw_ == CFI_type_char32_t;
   }
   constexpr bool IsLogical() const {
     return raw_ == CFI_type_Bool ||
-        (raw_ >= CFI_type_int_fast8_t && raw_ <= CFI_type_int_fast64_t);
+        (raw_ >= CFI_type_int_least8_t && raw_ <= CFI_type_int_least64_t);
   }
   constexpr bool IsDerived() const { return raw_ == CFI_type_struct; }
   constexpr bool IsIntrinsic() const { return IsValid() && !IsDerived(); }
 
   std::optional<std::pair<TypeCategory, int>> GetCategoryAndKind() const;
 
   bool operator==(const TypeCode &that) const { return raw_ == that.raw_; }
   bool operator!=(const TypeCode &that) const { return raw_ != that.raw_; }
 
 private:
   ISO::CFI_type_t raw_{CFI_type_other};
 };
 } // namespace Fortran::runtime
 #endif // FORTRAN_RUNTIME_TYPE_CODE_H_