[yocto] source added to -dbg pkg

[Kyle Farnsworth]

I would like to NOT put the source code within the ${PN}-dbg pkg and
keep it separate from my symbol binaries in that pkg.  Is there a way to
either turn off the collection of the source or allow me to put it in a
different pkg.  It could be useful to have some cases but not in all.

I have been using OE classic for years and just started using oe-core,
so this surprised me that it was doing this under the covers without
having to install it in the image dir first.

Thanks.