Revert "[upstreaming] Move Swift specific code in lldb-forward.h to own file"

This reverts commit 2ab31f3.

Author: Davide Italiano

lldb/include/lldb/lldb-forward.h

@@ -190,6 +190,9 @@ class SectionList;
 class SectionLoadHistory;
 class SectionLoadList;
 class Settings;
+class SwiftASTContext;
+class SwiftLanguageRuntime;
+class SwiftREPL;
 class SourceManager;
 class SourceManagerImpl;
 class StackFrame;
@@ -408,6 +411,7 @@ typedef std::weak_ptr<lldb_private::Section> SectionWP;
 typedef std::shared_ptr<lldb_private::SectionLoadList> SectionLoadListSP;
 typedef std::shared_ptr<lldb_private::SearchFilter> SearchFilterSP;
 typedef std::shared_ptr<lldb_private::Settings> SettingsSP;
+typedef std::shared_ptr<lldb_private::SwiftASTContext> SwiftASTContextSP;
 typedef std::unique_ptr<lldb_private::SourceManager> SourceManagerUP;
 typedef std::shared_ptr<lldb_private::StackFrame> StackFrameSP;
 typedef std::unique_ptr<lldb_private::StackFrame> StackFrameUP;
@@ -485,7 +489,5 @@ class StringRef;
 
 } // namespace llvm
 
-#include "swift-lldb-forward.h"
-
 #endif // #if defined(__cplusplus)
 #endif // LLDB_lldb_forward_h_