[gold][NPM] Use NPM with ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER

[MaskRay]

LGTM. OK, I think having LLVM_ENABLE_NEW_PASS_MANAGER in lld/ELF is probably also fine.

llvm/tools/gold/gold-plugin.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/CodeGen/CommandFlags.h"
 #include "llvm/Config/config.h" // plugin-api.h requires HAVE_STDINT_H
+#include "llvm/Config/llvm-config.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/LTO/Caching.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Object/Error.h"
 #include "llvm/Remarks/HotnessThresholdParser.h"
 #include "llvm/Support/CachePruning.h"
 #include "llvm/Support/CommandLine.h"
#endif
   static std::string cache_policy;
   // Additional options to pass into the code generator.
   // Note: This array will contain all plugin options which are not claimed
   // as plugin exclusive to pass to the code generator.
   static std::vector<const char *> extra;
   // Sample profile file path
   static std::string sample_profile;
   // New pass manager
-  static bool new_pass_manager = false;
+  static bool new_pass_manager = LLVM_ENABLE_NEW_PASS_MANAGER;
   // Debug new pass manager
   static bool debug_pass_manager = false;
   // Directory to store the .dwo files.
   static std::string dwo_dir;
   /// Statistics output filename.
   static std::string stats_file;
   // Asserts that LTO link has whole program visibility
   static bool whole_program_visibility = false;