[lldb/Plugin] s/LLDB_PLUGIN/LLDB_PLUGIN_DEFINE/ (NFC)

Rename LLDB_PLUGIN to LLDB_PLUGIN_DEFINE as Pavel suggested in D73067 to
avoid name conflict.

lldb/source/Plugins/OperatingSystem/Python/OperatingSystemPython.cpp

@@ -39,7 +39,7 @@
 using namespace lldb;
 using namespace lldb_private;
 
-LLDB_PLUGIN(OperatingSystemPython)
+LLDB_PLUGIN_DEFINE(OperatingSystemPython)
 
 void OperatingSystemPython::Initialize() {
   PluginManager::RegisterPlugin(GetPluginNameStatic(),