prlimit(2) returns ENOSYS on Linux 2.6.32-5-xen-amd64 as found on
hydra.gnu.org, and strace(1) doesn't recognize it.

--- glib-2.34.3/glib/tests/thread.c	2012-11-20 15:27:12.000000000 +0100
+++ glib-2.34.3/glib/tests/thread.c	2013-03-27 14:48:31.000000000 +0100
@@ -130,7 +130,7 @@ test_thread3 (void)
 static void
 test_thread4 (void)
 {
-#ifdef HAVE_PRLIMIT
+#if 0
   struct rlimit ol, nl;
   GThread *thread;
   GError *error;
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