Mark sockets on creation (socket()) and accept4().

Continued from: https://android-review.git.corp.google.com/#/c/95094/

Change-Id: Ib0b8f5d7c5013b91eae6bbc3847852eb355c7714
diff --git a/client/FwmarkClient.cpp b/client/FwmarkClient.cpp
index e360b4e..24c84c4 100644
--- a/client/FwmarkClient.cpp
+++ b/client/FwmarkClient.cpp
@@ -27,9 +27,8 @@
 
 }  // namespace
 
-bool FwmarkClient::shouldSetFwmark(int sockfd, const sockaddr* addr) {
-    return sockfd >= 0 && addr && (addr->sa_family == AF_INET || addr->sa_family == AF_INET6) &&
-           !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
+bool FwmarkClient::shouldSetFwmark(int family) {
+    return (family == AF_INET || family == AF_INET6) && !getenv("ANDROID_NO_USE_FWMARK_CLIENT");
 }
 
 FwmarkClient::FwmarkClient() : mChannel(-1) {