DeclUnloader: Remove extra check isInstantiatedInPCH

This effectively reverts commit 74472caaa9 ("[cling] Fixes issue in
DeclUnloader: do not unload templates intantiated in the PCH"), it's
not needed anymore, all tests pass and the snippet in the summary of
root-project/root#4447 works, but it filters
too many declarations from the unloader.

lib/Interpreter/DeclUnloader.cpp

@@ -473,21 +473,6 @@ namespace {
 namespace cling {
   using namespace clang;
 
-  ///\brief Return whether `D' is a template that was first instantiated non-
-  /// locally, i.e. in a PCH/module. If `D' is not an instantiation, return
-  /// false.
-  bool DeclUnloader::isInstantiatedInPCH(const Decl* D) {
-    SourceManager& SM = D->getASTContext().getSourceManager();
-    if (const auto FD = dyn_cast<FunctionDecl>(D))
-      return FD->isTemplateInstantiation() &&
-             !SM.isLocalSourceLocation(FD->getPointOfInstantiation());
-    else if (const auto CTSD = dyn_cast<ClassTemplateSpecializationDecl>(D))
-      return !SM.isLocalSourceLocation(CTSD->getPointOfInstantiation());
-    else if (const auto VTSD = dyn_cast<VarTemplateSpecializationDecl>(D))
-      return !SM.isLocalSourceLocation(VTSD->getPointOfInstantiation());
-    return false;
-  }
-
   void DeclUnloader::resetDefinitionData(TagDecl* decl) {
     auto canon = dyn_cast<CXXRecordDecl>(decl->getCanonicalDecl());
     assert(canon && "Only CXXRecordDecl have DefinitionData");

lib/Interpreter/DeclUnloader.h

@@ -60,7 +60,7 @@ namespace cling {
     ///\returns true on success.
     ///
     bool UnloadDecl(clang::Decl* D) {
-      if (D->isFromASTFile() || isInstantiatedInPCH(D))
+      if (D->isFromASTFile())
         return true;
       return Visit(D);
     }
@@ -270,8 +270,6 @@ namespace cling {
     ///
     void CollectFilesToUncache(clang::SourceLocation Loc);
 
-    bool isInstantiatedInPCH(const clang::Decl *D);
-
     template <typename T>
     bool VisitRedeclarable(clang::Redeclarable<T>* R, clang::DeclContext* DC);
   };