servers: start with refcount for opened files

src/servers/syscalls.c

@@ -77,6 +77,8 @@ void handleSyscallResponse(const SyscallHeader *hdr) {
         file = (FileDescriptor *) iod->data;
         file->process = p;
         file->id = opencmd->id;     // unique ID for device files
+        file->refCount = 1;
+
         strcpy(file->abspath, opencmd->abspath);
         strcpy(file->device, opencmd->device);
         strcpy(file->path, opencmd->path);