This change happened upstream in this commit:

commit ae65d4f3c3995279ca458c460ebf8bab1885fa03
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date:   Mon Mar 13 18:42:35 2017 +0000

     Remove the str(n)dup inlines from string/bits/string2.h.

diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index 317413c9ef1559e6..b3d0a5ca74d926bb 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -1106,7 +1106,7 @@ gaih_inet (const char *name, const struct gaih_service *service,
 		  canonbuf = NULL;
 		else
 		  {
-		    canon = strdup (canon);
+		    canon = __strdup (canon);
 		    if (canon == NULL)
 		      {
 			result = -EAI_MEMORY;