Report getaddrinfo failures correctly.

Also move us off the "convenience" function because you can't get useful
error reporting from it.

Change-Id: I5fcc6a6d762f5f60906980a7835f01a35045be65
diff --git a/adb/adb_utils.h b/adb/adb_utils.h
index e0aa1ba..d1a3f5f 100644
--- a/adb/adb_utils.h
+++ b/adb/adb_utils.h
@@ -39,4 +39,6 @@
                          std::string* host, int* port,
                          std::string* error);
 
+int network_connect(const std::string& host, int port, int type, int timeout, std::string* error);
+
 #endif