Partial backport. Only the i686 piece is needed in glibc 2.17, and

the x86_64 piece doesn't apply anyway because we lack the multiarch

implementations present in upstream. Instead the the x86_64 piece

is fixed by glibc-rh1447808-2.patch. 

commit e826574c985a15a500262f2fbd21c7e9259d3d11 (origin/master, origin/HEAD)

Author: Florian Weimer <fweimer@redhat.com>

Date:   Tue Jun 12 15:00:33 2018 +0200

    x86: Make strncmp usable from rtld

    Due to the way the conditions were written, the rtld build of strncmp

    ended up with no definition of the strncmp symbol at all: The

    implementations were renamed for use within an IFUNC resolver, but the

    IFUNC resolver itself was missing (because rtld does not use IFUNCs).

    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

Index: glibc-2.17-c758a686/sysdeps/i386/i686/multiarch/strncmp-c.c

===================================================================

--- glibc-2.17-c758a686.orig/sysdeps/i386/i686/multiarch/strncmp-c.c

+++ glibc-2.17-c758a686/sysdeps/i386/i686/multiarch/strncmp-c.c

@@ -1,4 +1,4 @@

-#ifdef SHARED

+#if defined (SHARED) && IS_IN (libc)

 # define STRNCMP __strncmp_ia32

 # undef libc_hidden_builtin_def

 # define libc_hidden_builtin_def(name)  \