kdl-parser: add explicit dependency on libeigen

libeigen is an interface dependency needed by orocos-kdl and
orocos-kdl does export this dependency, but it does so with
a hardcoded absolute path pointing to the sysroot where
orocos-kdl was built. In case the sysroot doesn't exist
the compiler can't find libeigen's headers.

Unfortunately orocos-kdl's CMakeList.txt doesn't use
per-target include dirs, but global ones. I don't know
an easy way how to make them relocatable.

The easiest way to fix it is to add the explicit dependency
on libeigen to kdl-parser's CMakeList.txt. Anyway it's already
been declarated as a dependency in kdl-parser's recipe.

Signed-off-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>