talloc: fix swig dependencies

* depens on swig-native to make sure that the talloc.i always be
  installed;

* remove relative path that from `swig -swiglib`:

    ${D}/usr/bin/../share -> ${D}/usr/share

  This prevents 'install' from creraing empty dir: ${D}${bindir};

* fix the path to talloc.i for separate build.

Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>