llvm: correct fix for the multilib libdir

* If llvm.inc is used for native and nativesdk class packages, the
  resulting llvm-config is broken since "${base_libdir}" is prefixed
  with the full patch to sysroot
* Replace "/lib" with "/${baselib}" instead of "${base_libdir}" as
  "${base_libdir}" is the full path and "${baselib}" is the name of
  the multilib directory.

Signed-off-by: Jacob Stiffler <j-stiffler@ti.com>
Acked-by: Denys Dmytriyenko <denys@ti.com>
Tested-by: Denys Dmytriyenko <denys@ti.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>