The check has no AC_MGS_RESULT finish helper
and gets called as
    set ``
on gcc-6 which clutters ./configure output.

One of fallouts of https://bugs.gentoo.org/598798
diff --git a/configure.ac b/configure.ac
index 34a7f71..0f06f57 100644
--- a/configure.ac
+++ b/configure.ac
@@ -574,7 +574,2 @@ if test "$GCC" = "yes" ; then
 
-  AC_MSG_CHECKING(for glibc...)
-  set `printf '%b\n' '#include <features.h>\nXXAaZZ __GLIBC__'|${CC-cc} -E -|awk '/XXAaZZ/ {print $2}'`
-  if test "$1" = "__GLIBC__"; then
-    AC_MSG_ERROR([Sorry, you need glibc.])
-  fi
 fi