[clang] [Modules] Record whether VarDecl initializers contain side effects (PR #143739)

[Chuanqi Xu via cfe-commits]

================
@@ -195,6 +196,10 @@ class ExternalASTSource : public RefCountedBase<ExternalASTSource> {
   /// module.
   virtual bool wasThisDeclarationADefinition(const FunctionDecl *FD);
 
+  virtual bool hasInitializerWithSideEffects(const VarDecl *VD) const {
----------------
ChuanqiXu9 wrote:

Generally, every time we add an interface to ExternalASTSource, we need to add one for `MultiplexExternalSemaSource`.

https://github.com/llvm/llvm-project/pull/143739