[lldb] Make sure Status is updated in GetFrameBaseValue

This fixes the following assertion: "Cannot create Expected<T> from
Error success value." The problem was that GetFrameBaseValue return
false without updating the Status argument. This patch makes sure that
every return path updates the Status if the pointer is valid.

Author: JDevlieghere

lldb/source/Target/StackFrame.cpp

@@ -1084,7 +1084,9 @@ bool StackFrame::GetFrameBaseValue(Scalar &frame_base, Status *error_ptr) {
   if (!m_cfa_is_valid) {
     m_frame_base_error = Status::FromErrorString(
         "No frame base available for this historical stack frame.");
-    return false;
+    if (error_ptr)
+      *error_ptr = m_frame_base_error.Clone();
+    return m_frame_base_error.Success();
   }
 
   if (m_flags.IsClear(GOT_FRAME_BASE)) {