Use LLVM definitions for Swift section names (NFC)

lib/FrontendTool/FrontendTool.cpp

@@ -36,7 +36,6 @@
 #include "swift/AST/TBDGenRequests.h"
 #include "swift/AST/TypeRefinementContext.h"
 #include "swift/Basic/Defer.h"
-#include "swift/Basic/Dwarf.h"
 #include "swift/Basic/Edit.h"
 #include "swift/Basic/FileSystem.h"
 #include "swift/Basic/LLVMInitialize.h"
@@ -2241,10 +2240,6 @@ int swift::performFrontend(ArrayRef<const char *> Args,
              trace.emplace(*buffer);
            });
 
-  // Setting DWARF Version depend on platform
-  IRGenOptions &IRGenOpts = Invocation.getIRGenOptions();
-  IRGenOpts.DWARFVersion = swift::DWARFVersion;
-
   // The compiler invocation is now fully configured; notify our observer.
   if (observer) {
     observer->parsedArgs(Invocation);