Replace android_open_proxy with dns_open_proxy

remove android_open_proxy and use dns_open_proxy instead of it.
dns_open_proxy is in libnetd_client and
it does the same thing as android_open_proxy except return value.
It returns fd directly now.

Test: build, dns works fine
Change-Id: I984743fb50b23eeb9a7d24e9fc347832acfe2afe
diff --git a/libc/bionic/NetdClient.cpp b/libc/bionic/NetdClient.cpp
index a5c519e..87eec27 100644
--- a/libc/bionic/NetdClient.cpp
+++ b/libc/bionic/NetdClient.cpp
@@ -58,6 +58,8 @@
     netdClientInitFunction(netdClientHandle, "netdClientInitNetIdForResolv",
                            &__netdClientDispatch.netIdForResolv);
     netdClientInitFunction(netdClientHandle, "netdClientInitSocket", &__netdClientDispatch.socket);
+    netdClientInitFunction(netdClientHandle, "netdClientInitDnsOpenProxy",
+                           &__netdClientDispatch.dnsOpenProxy);
 }
 
 static pthread_once_t netdClientInitOnce = PTHREAD_ONCE_INIT;