Add runtime detection of V8 memory cage #3384

When using the V8 memory cage, Buffers cannot be wrapped and then
later freed via a callback. When the cage is detected via a throw,
instead fall back to copying Buffer contents to V8 memory.

This approach will be used by Electron 21+ and you should expect
reduced performance and increased memory consumption/fragmentation.

src/common.cc

@@ -76,6 +76,14 @@ namespace sharp {
     }
     return vector;
   }
+  Napi::Buffer<char> NewOrCopyBuffer(Napi::Env env, char* data, size_t len) {
+    try {
+      return Napi::Buffer<char>::New(env, data, len, FreeCallback);
+    } catch (Napi::Error const &err) {}
+    Napi::Buffer<char> buf = Napi::Buffer<char>::Copy(env, data, len);
+    FreeCallback(nullptr, data);
+    return buf;
+  }
 
   // Create an InputDescriptor instance from a Napi::Object describing an input image
   InputDescriptor* CreateInputDescriptor(Napi::Object input) {