add windows-mutex optional dependency

npm-shrinkwrap.json

@@ -460,6 +460,22 @@
           "resolved": "https://registry.npmjs.org/pend/-/pend-1.2.0.tgz"
         }
       }
+    },
+    "windows-mutex": {
+      "version": "0.1.3",
+      "from": "windows-mutex@0.1.3",
+      "dependencies": {
+        "bindings": {
+          "version": "1.2.1",
+          "from": "bindings@>=1.2.1 <2.0.0",
+          "resolved": "https://registry.npmjs.org/bindings/-/bindings-1.2.1.tgz"
+        },
+        "nan": {
+          "version": "2.1.0",
+          "from": "nan@>=2.1.0 <3.0.0",
+          "resolved": "https://registry.npmjs.org/nan/-/nan-2.1.0.tgz"
+        }
+      }
     }
   }
 }

package.json

@@ -12,7 +12,7 @@
   },
   "scripts": {
     "test": "node node_modules/mocha/bin/_mocha",
-		"preinstall": "node build/npm/preinstall.js",
+    "preinstall": "node build/npm/preinstall.js",
     "postinstall": "npm --prefix extensions/csharp-o/ install extensions/csharp-o/ && npm --prefix extensions/vscode-api-tests/ install extensions/vscode-api-tests/"
   },
   "dependencies": {
@@ -89,5 +89,8 @@
     "ghooks": {
       "pre-commit": "node build/gulpfile.hygiene.js"
     }
+  },
+  "optionalDependencies": {
+    "windows-mutex": "^0.1.3"
   }
 }