[lldb] Provide a getter for m_materializer_up in LLVMUserExpression instead of relying on it being accessible.

Summary:
Motivated by Swift using the materializer in a few places which requires us to add this getter ourselves.
We also need a setter, but let's keep this minimal to unblock the downstream reverts in Swift.

Reviewers: davide

Reviewed By: davide

Subscribers: abidh, JDevlieghere, lldb-commits

Tags: #upstreaming_lldb_s_downstream_patches, #lldb

Differential Revision: https://reviews.llvm.org/D69714
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
index da1ca78..60592ca 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
@@ -576,7 +576,7 @@
 
   auto on_exit = llvm::make_scope_exit([this]() { ResetDeclMap(); });
 
-  if (!DeclMap()->WillParse(exe_ctx, m_materializer_up.get())) {
+  if (!DeclMap()->WillParse(exe_ctx, GetMaterializer())) {
     diagnostic_manager.PutString(
         eDiagnosticSeverityError,
         "current process state is unsuitable for expression parsing");
@@ -764,7 +764,7 @@
 
   auto on_exit = llvm::make_scope_exit([this]() { ResetDeclMap(); });
 
-  if (!DeclMap()->WillParse(exe_ctx, m_materializer_up.get())) {
+  if (!DeclMap()->WillParse(exe_ctx, GetMaterializer())) {
     diagnostic_manager.PutString(
         eDiagnosticSeverityError,
         "current process state is unsuitable for expression parsing");