Signed-off-by: Stefan Herbrechtsmeier <stefan@herbrechtsmeier.net>

Signed-off-by: Stefan Herbrechtsmeier <stefan@herbrechtsmeier.net>

Before this commit, the following sequence of bitbake commands
failed because the path was set during compile time, and not at
runtime. After the patch from Dirk Thomas, the following sequence
now works.

bitbake nodelet-topic-tools -c cleansstate && \
bitbake dynamic-reconfigure && bitbake nodelet-topic-tools

To compile nodelet-topic-tools, we must provide a working
dynamic-reconfigure in the native sysroot. This requires
some adjustments to the native versions of the required
python modules.

In particular, the following tasks ran successfully for this
commit:

This command tests compiling rospack-native:
rm bitbake.lock cache/ sstate-cache/ tmp-eglibc/ -rf && bitbake rospack-native

This command tests compiling roslib-native:
rm bitbake.lock cache/ sstate-cache/ tmp-eglibc/ -rf && bitbake roslib-native

As nodelet-topic-tools uses rospack-native and roslib-native to
some extent (dependency: rospack-native -> roslib-native ->
dynamic-reconfigure-native -> nodelet-topic-tools), this command
tests running rospack-native and roslib-native:
rm bitbake.lock cache/ sstate-cache/ tmp-eglibc/ -rf && bitbake nodelet-topic-tools

This command tests compiling rospack and roslib:
rm bitbake.lock cache/ sstate-cache/ tmp-eglibc/ -rf && bitbake rospack
rm bitbake.lock cache/ sstate-cache/ tmp-eglibc/ -rf && bitbake roslib

All these command run with this commit without errors, and
future commits to these files should keep them run without
errors or justify modifications with better tests.

A minor open issue related to rospack is issue #116
(cf. https://github.com/bmwcarit/meta-ros/issues/116).

This commit incorporates feedback from Stefan Herbrechtsmeier.