--- /dev/null
+#serial 1
+
+dnl From Gordon Matzigkeit.
+dnl Test for the GNU C Library.
+dnl FIXME: this should migrate into libit.
+
+AC_DEFUN(AM_GLIBC,
+[AC_CACHE_CHECK(whether we are using the GNU C Library,
+ ac_cv_gnu_library,
+[AC_EGREP_CPP([Thanks for using GNU],
+[#include <features.h>
+#ifdef __GNU_LIBRARY__
+Thanks for using GNU
+#endif],
+ ac_cv_gnu_library=yes, ac_cv_gnu_library=no)])
+AC_CACHE_CHECK(for version 2 of the GNU C Library,
+ ac_cv_glibc,
+[AC_EGREP_CPP([Thanks for using GNU too],
+[#include <features.h>
+#ifdef __GLIBC__
+Thanks for using GNU too
+#endif],
+ ac_cv_glibc=yes, ac_cv_glibc=no)])])dnl