Create libsampler as V8 sampler library.

src/v8.gyp

Index: src/v8.gyp
diff --git a/src/v8.gyp b/src/v8.gyp
index c5b261f2cddc8742235bd105a6689c6ecdd624b7..cfc42e59bccb5e4c5f556a6c7f15110096361292 100644
--- a/src/v8.gyp
+++ b/src/v8.gyp
@@ -1923,6 +1923,35 @@
       },
     },
     {
+      'target_name': 'v8_libsampler',
+      'type': 'static_library',
+      'variables': {
+        'optimize': 'max',
+      },
+      'dependencies': [
+        'v8_base',
+      ],
+      'include_dirs+': [
+        '..',
+      ],
+      'sources': [
+        'libsampler/v8-sampler.cc',
+        'libsampler/v8-sampler.h'
+      ],
+      'conditions': [
+        ['want_separate_host_toolset==1', {
+          'toolsets': ['host', 'target'],
+        }, {
+          'toolsets': ['target'],
+        }],
+      ],
+      'direct_dependent_settings': {
+        'include_dirs': [
+          '../include',
+        ],
+      },
+    },
+    {
       'target_name': 'natives_blob',
       'type': 'none',
       'conditions': [