[lldb/Target] Remove outdated code

Arg0 callback does work.

Author: tkrasnukha

lldb/include/lldb/Target/Target.h

@@ -211,7 +211,7 @@ class TargetProperties : public Properties {
 
   void SetDisplayRecognizedArguments(bool b);
 
-  const ProcessLaunchInfo &GetProcessLaunchInfo();
+  const ProcessLaunchInfo &GetProcessLaunchInfo() const;
 
   void SetProcessLaunchInfo(const ProcessLaunchInfo &launch_info);
 

lldb/source/Target/Target.cpp

@@ -4196,8 +4196,7 @@ void TargetProperties::SetNonStopModeEnabled(bool b) {
   m_collection_sp->SetPropertyAtIndexAsBoolean(nullptr, idx, b);
 }
 
-const ProcessLaunchInfo &TargetProperties::GetProcessLaunchInfo() {
-  m_launch_info.SetArg0(GetArg0()); // FIXME: Arg0 callback doesn't work
+const ProcessLaunchInfo &TargetProperties::GetProcessLaunchInfo() const {
   return m_launch_info;
 }