Query libnetd_client for the appropriate netId for host resolution.

If libnetd_client can't be found, operate as before and use the default netId
potentially overriden by a more specific netId passed in to
android_get*fornet().

(cherry picked from commit 559c7842cc)

Change-Id: I42ef3293172651870fb46d2de22464c4f03e8e0b

libc/bionic/NetdClientDispatch.cpp

@@ -25,9 +25,14 @@
 extern "C" __socketcall int __accept(int, sockaddr*, socklen_t*);
 extern "C" __socketcall int __connect(int, const sockaddr*, socklen_t);
 
+static unsigned fallBackNetIdForResolv(unsigned netId) {
+    return netId;
+}
+
 // This structure is modified only at startup (when libc.so is loaded) and never
 // afterwards, so it's okay that it's read later at runtime without a lock.
 __LIBC_HIDDEN__ NetdClientDispatch __netdClientDispatch __attribute__((aligned(32))) = {
     __accept,
     __connect,
+    fallBackNetIdForResolv,
 };