By default, vsyscall is only enabled when target host is i686. This should
not be related to build optimizations and it should always be enabled since
it is the kernel that chooses what interface to expose.  --WT

diff -urN glibc-2.3.6-dist/nptl/sysdeps/unix/sysv/linux/i386/dl-sysdep.h glibc-2.3.6/nptl/sysdeps/unix/sysv/linux/i386/dl-sysdep.h
--- glibc-2.3.6-dist/nptl/sysdeps/unix/sysv/linux/i386/dl-sysdep.h	2003-06-16 07:28:46 +0200
+++ glibc-2.3.6/nptl/sysdeps/unix/sysv/linux/i386/dl-sysdep.h	2010-11-14 10:05:10 +0100
@@ -43,7 +43,7 @@
    linker and dl code in libc.a has to be able to load i686 compiled
    libraries.  */
 #define NEED_DL_SYSINFO	1
-#undef USE_DL_SYSINFO
+#define USE_DL_SYSINFO  1
 
 #if defined NEED_DL_SYSINFO && !defined __ASSEMBLER__
 extern void _dl_sysinfo_int80 (void) attribute_hidden;