scripts/postinst-intercepts: create separete hooks for multilib

scripts/postinst-intercepts: create separete hooks for multilib

When using multilib, the hooks for lib32/lib64 must be different because
the libdir/base_libdir point to different locations. Postinstalls
calling postint_intercept script must pass the mlprefix in the 3rd
argument.

(From OE-Core rev: 2c5c6e3ffcd561c25a34603922b622449f677a34)

Signed-off-by: Laurentiu Palcu <laurentiu.palcu@intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>