perf: Enable debug/source packaging

This was disabled in 2014[1] due to an error message which as far
as I can tell, no longer occurs.

Having debug information and source files present will make debugging
reproducibility issues much easier so remove this line as it appears
no longer needed.

Fix up a few files which have buildpaths in them to avoid QA warnings
and reproducubility issues.

[1] OE-Core revision c1b5a262

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>