kernel/linux: deprecate copying headers from pre-instaleld headers

No-one ever inquired about this feature. Due to the way it works, it is
rather unlikely that every user used a properly-formatted tarball, or a
properly structured directory as imput.

Beside, it is not really easy to maintain: I just spent one full day
remembering how it worked... Sigh... :-(

Just deprecate this, until next release, or until someone complains.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # Overall toolchain configuration: paths, jobs, etc...

 # Allow unconditional usage of tristates

 config MODULES

     bool

     default y

 menu "Paths and misc options"

 source "config/global/ct-behave.in"

 source "config/global/paths.in"

 source "config/global/download.in"

 source "config/global/extract.in"

 source "config/global/build-behave.in"

 source "config/global/logging.in"

 endmenu