[commited,hurd] Add __libc_init_secure stub

[Samuel Thibault]

    csu/libc-start.c now insists on calling __libc_init_secure, while the Hurd
    port already implements it "very early" in dl-sysdep.c and init-first.c
    
            * sysdeps/mach/hurd/enbl-secure.c (__libc_init_secure): Define
            function.

diff --git a/sysdeps/mach/hurd/enbl-secure.c b/sysdeps/mach/hurd/enbl-secure.c
index 9aeb0fafa6..87a8f93013 100644
--- a/sysdeps/mach/hurd/enbl-secure.c
+++ b/sysdeps/mach/hurd/enbl-secure.c
@@ -21,3 +21,10 @@
    In the shared library, the `__libc_enable_secure' variable is defined
    by the dynamic linker in dl-sysdep.c and set there.
    In the static library, it is defined in init-first.c and set there.  */
+
+#include <libc-internal.h>
+
+void
+__libc_init_secure (void)
+{
+}