libc: use original 'gai_strerror()' implementation

This commit removes the dummy 'gai_strerror()' implementation in
favor of the one provided in the contrib sources to allow for better
diagnosing of DNS related problems.

As long as NLS is not set the implementation looks up the error string
via the error-code directly.

Fixes #5464.

repos/libports/lib/mk/libc-net.mk

@@ -5,6 +5,7 @@ SRC_C = getservent.c nsdispatch.c nsparser.c nslexer.c
 
 # needed for getaddrinfo()
 SRC_C += getaddrinfo.c
+SRC_C += gai_strerror.c
 
 # needed for getnameinfo()
 SRC_C += getnameinfo.c name6.c

repos/libports/lib/mk/libc.mk

@@ -12,7 +12,7 @@ LIBS  += base vfs
 # Back end
 #
 SRC_CC = atexit.cc dummies.cc rlimit.cc sysctl.cc \
-         issetugid.cc errno.cc gai_strerror.cc time.cc alarm.cc \
+         issetugid.cc errno.cc time.cc alarm.cc \
          malloc.cc progname.cc fd_alloc.cc file_operations.cc \
          plugin.cc plugin_registry.cc select.cc exit.cc environ.cc sleep.cc \
          pread_pwrite.cc readv_writev.cc poll.cc \

repos/libports/src/lib/libc/gai_strerror.cc

@@ -1,21 +0,0 @@
-/*
- * \brief  C-library back end
- * \author Christian Prochaska
- * \date   2010-05-16
- */
-
-/*
- * Copyright (C) 2010-2017 Genode Labs GmbH
- *
- * This file is part of the Genode OS framework, which is distributed
- * under the terms of the GNU Affero General Public License version 3.
- */
-
-#include <base/log.h>
-
-extern "C" const char *gai_strerror(int errcode)
-{
-	static const char *result = "gai_strerror called, not yet implemented!";
-	Genode::log(__func__, ": ", result);
-	return result;
-}