Revert "daemon-helper: use _nm_strerror_r() to avoid non-thread-safe strerror()"

The function is not backported to this branch, and it's not 100%
necessary.

This reverts commit 93359f2b32.

(cherry picked from commit 29de766b9e)

src/nm-daemon-helper/nm-daemon-helper.c

@@ -120,8 +120,8 @@ cmd_resolve_address(void)
                     service,
                     ret,
                     gai_strerror(ret),
-                    errsv,
-                    _nm_strerror_r(errsv, buf, sizeof(buf)));
+                    errno,
+                    strerror(errno));
         } else {
             fprintf(stderr,
                     "getnameinfo() via service '%s' failed: %d (%s)\n",