[flang] fulfill -Msave/-fno-automatic in main programs too

`semantics::IsSaved()` was not applying -Msave/-fno-automatic for main programs.
This caused issues since lowering relies on it to allocate static
variables. This did not match nvfortran/gfortran behaviors where
-fno-automatic/-Msave control the static allocation of scalars in
main programs.

Some program may rely on main program scalars to be statically allocated in
bss (and therefore initialized to zero) with -Msave/-fno-automatic
flags.

Differential Revision: https://reviews.llvm.org/D121603

flang/lib/Evaluate/tools.cpp

@@ -1324,12 +1324,14 @@ bool IsSaved(const Symbol &original) {
     // BLOCK DATA entities must all be in COMMON,
     // which was checked above.
     return true;
-  } else if (scope.kind() == Scope::Kind::Subprogram &&
-      scope.context().languageFeatures().IsEnabled(
-          common::LanguageFeature::DefaultSave) &&
-      !(scope.symbol() && scope.symbol()->attrs().test(Attr::RECURSIVE))) {
-    // -fno-automatic/-save/-Msave option applies to objects in
-    // executable subprograms unless they are explicitly RECURSIVE.
+  } else if (scope.context().languageFeatures().IsEnabled(
+                 common::LanguageFeature::DefaultSave) &&
+      (scopeKind == Scope::Kind::MainProgram ||
+          (scope.kind() == Scope::Kind::Subprogram &&
+              !(scope.symbol() &&
+                  scope.symbol()->attrs().test(Attr::RECURSIVE))))) {
+    // -fno-automatic/-save/-Msave option applies to all objects in executable
+    // main programs and subprograms unless they are explicitly RECURSIVE.
     return true;
   } else if (symbol.test(Symbol::Flag::InDataStmt)) {
     return true;