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/dns/net/getaddrinfo.c b/libc/dns/net/getaddrinfo.c
index f1488a9..4e1aa61 100644
--- a/libc/dns/net/getaddrinfo.c
+++ b/libc/dns/net/getaddrinfo.c
@@ -422,11 +422,10 @@
 		return EAI_NODATA;
 	}
 
-	FILE* proxy = android_open_proxy();
+	FILE* proxy = fdopen(__netdClientDispatch.dnsOpenProxy(), "r+");
 	if (proxy == NULL) {
 		return EAI_SYSTEM;
 	}
-
 	netid = __netdClientDispatch.netIdForResolv(netid);
 
 	// Send the request.