[build] Introduce an embedder version string

src/version.h

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_VERSION_H_
 #define V8_VERSION_H_
 
 #include "src/base/functional.h"
 #include "src/vector.h"
 
 namespace v8 {
 namespace internal {
 
 class Version {
  public:
   // Return the various version components.
   static int GetMajor() { return major_; }
   static int GetMinor() { return minor_; }
   static int GetBuild() { return build_; }
   static int GetPatch() { return patch_; }
+  static const char* GetEmbedder() { return embedder_; }
   static bool IsCandidate() { return candidate_; }
   static uint32_t Hash() {
     return static_cast<uint32_t>(
         base::hash_combine(major_, minor_, build_, patch_));
   }
 
   // Calculate the V8 version string.
   static void GetString(Vector<char> str);
 
   // Calculate the SONAME for the V8 shared library.
   static void GetSONAME(Vector<char> str);
 
   static const char* GetVersion() { return version_string_; }
 
  private:
   // NOTE: can't make these really const because of test-version.cc.
   static int major_;
   static int minor_;
   static int build_;
   static int patch_;
+  static const char* embedder_;
   static bool candidate_;
   static const char* soname_;
   static const char* version_string_;
 
   // In test-version.cc.
   friend void SetVersion(int major, int minor, int build, int patch,
-                         bool candidate, const char* soname);
+                         const char* embedder, bool candidate,
+                         const char* soname);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_VERSION_H_