prelink: Fix Segmentation fault error when prelink qemu

prelink: Fix Segmentation fault error when prelink qemu

The info->resolvetls might be NULL according to src/prelink.c:
[snip]
 /* Dynamic linker does not depend on any other library,
    all symbols resolve to themselves with the exception
    of SHN_UNDEF symbols which resolve to 0.  */
if (info->symtab[r_sym].st_shndx == SHN_UNDEF)
  {
    info->resolveent = NULL;
    info->resolvetls = NULL;
[snip]

So we must check it before use its members, otherwise, there might be
Segmentation fault error.

Fixed:
MACHINE = "qemumips"
IMAGE_INSTALL_append = " qemu"
$ bitbake core-image-minimal
[snip]
| /path/to/qemumips-poky-linux/core-image-minimal/1.0-r0/temp/run.prelink_image.1000: line 111:  1010 Segmentation fault      (core dumped)
[snip]

(From OE-Core rev: 7f5d6f6b70cb1eb486d3ff5c029fc3c6202fc826)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>