[flang] Dodge gcc 8.2.0 build problem (NFC)

[klausler]

Summary

Add explicit member initializers to the declarations of
some constexpr values added in a recent patch to avoid an
apparent problem with gcc 8.2.0 with default initializers.

[PeteSteinfeld]

All of the flang front end builds without warnings, and everything tests cleanly.

flang/lib/Evaluate/intrinsics.cpp

struct IntrinsicDummyArgument {
   llvm::raw_ostream &Dump(llvm::raw_ostream &) const;
 };
 
 // constexpr abbreviations for popular arguments:
 // DefaultingKIND is a KIND= argument whose default value is the appropriate
 // KIND(0), KIND(0.0), KIND(''), &c. value for the function result.
 static constexpr IntrinsicDummyArgument DefaultingKIND{"kind",
     {IntType, KindCode::kindArg}, Rank::scalar,
-    Optionality::defaultsToDefaultForResult};
+    Optionality::defaultsToDefaultForResult, common::Intent::In};
 // MatchingDefaultKIND is a KIND= argument whose default value is the
 // kind of any "Same" function argument (viz., the one whose kind pattern is
 // "same").
 static constexpr IntrinsicDummyArgument MatchingDefaultKIND{"kind",
-    {IntType, KindCode::kindArg}, Rank::scalar,
-    Optionality::defaultsToSameKind};
+    {IntType, KindCode::kindArg}, Rank::scalar, Optionality::defaultsToSameKind,
+    common::Intent::In};
 // SizeDefaultKind is a KIND= argument whose default value should be
 // the kind of INTEGER used for address calculations, and can be
 // set so with a compiler flag; but the standard mandates the
 // kind of default INTEGER.
 static constexpr IntrinsicDummyArgument SizeDefaultKIND{"kind",
-    {IntType, KindCode::kindArg}, Rank::scalar,
-    Optionality::defaultsToSizeKind};
-static constexpr IntrinsicDummyArgument RequiredDIM{
-    "dim", {IntType, KindCode::dimArg}, Rank::scalar, Optionality::required};
-static constexpr IntrinsicDummyArgument OptionalDIM{
-    "dim", {IntType, KindCode::dimArg}, Rank::scalar, Optionality::optional};
-static constexpr IntrinsicDummyArgument OptionalMASK{
-    "mask", AnyLogical, Rank::conformable, Optionality::optional};
+    {IntType, KindCode::kindArg}, Rank::scalar, Optionality::defaultsToSizeKind,
+    common::Intent::In};
+static constexpr IntrinsicDummyArgument RequiredDIM{"dim",
+    {IntType, KindCode::dimArg}, Rank::scalar, Optionality::required,
+    common::Intent::In};
+static constexpr IntrinsicDummyArgument OptionalDIM{"dim",
+    {IntType, KindCode::dimArg}, Rank::scalar, Optionality::optional,
+    common::Intent::In};
+static constexpr IntrinsicDummyArgument OptionalMASK{"mask", AnyLogical,
+    Rank::conformable, Optionality::optional, common::Intent::In};
 
 struct IntrinsicInterface {
   static constexpr int maxArguments{7}; // if not a MAX/MIN(...)
   const char *name{nullptr};
   IntrinsicDummyArgument dummy[maxArguments];
   TypePattern result;
   Rank rank{Rank::elemental};
   IntrinsicClass intrinsicClass{IntrinsicClass::elementalFunction};