cracklib: fix QA warning about unsafe references in binaries

cracklib: fix QA warning about unsafe references in binaries

If enable test 'unsafe-references-in-binaries', build libpam will get
following warnings:

WARNING: QA Issue: libpam: /lib/security/pam_cracklib.so, installed in \
the base_prefix, requires a shared library under exec_prefix (/usr): \
libcrack.so.2 => /usr/lib/libcrack.so.2

(From OE-Core rev: 7ffe63c4a4f6b3adfea97eed4c0452c287784663)

Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>