meta/lib/oe/package_manager.py: deprecate 'exit 1' as a way to defer to first boot
'exit 1' is not optimal for two reasons:
1) Code is hard to read; it is not obvious that it means 'defer what follows to first boot'.
2) Worse, this hides actual errors in the scriptlets; there is no difference between scriptlet
failing because it's intended to be run on target and scriptlet failing because there's a bug or
a regression somewhere.
The new, supported way is to place the code that has to run on target into pkg_postinst_ontarget(),
or, if a more fine-tuned control is required, call 'postinst-intercepts defer_to_first_boot' from
pkg_postinst() to explicitly request deferral to first boot.
Signed-off-by: Alexander Kanavin <alexander.kanavin@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
