qemu.inc: depend on qemu-native only with runqemu DISTRO_FEATURE

* qemu images are usefull even without qemu installed on build machine.
  Some people are building on one machine, but then downloading images
  somewhere else to test them.
* use new "runqemu" DISTRO_FEATURE and BACKFILL it so the behavior stays
  the same, unless disabled by DISTRO_FEATURES_BACKFILL_CONSIDERED

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
docbook-sgml-dtd: add 4.3 version

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
package-test: add test recipes

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
console-tools, kbd: add RREPLACES/RPROVIDES/RCONFLICTS combo between PN-dbg

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
oe-core: add world-image

* this depends on newer bitbake
* similar to world target, but collects all PACKAGES
* recipes marked with EXCLUDE_FROM_WORLD are excluded from world as well
  as world-image
* recipes marked with EXCLUDE_FROM_WORLD_IMAGE are excluded completely
  from world-image, sometimes you can build 2 recipes in same sysroot,
  but cannot install them in the same image
* PACKAGES listed in EXCLUDE_PACKAGES_FROM_WORLD_IMAGE are also
  excluded. You can remove e.g. ${PN}-dbg, but keep all other PACKAGES.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
initrdscripts: exclude conflicting packages from world-image

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
sstatesig: introduce SignatureGeneratorOEBasicHashLite

* Rebuilds packages when:
  a) If you edit patches of a given recipe it will rebuild.
  b) If you change a task like do_configure, things after it will rerun in
     a given recipe.
  c) If a dependent task in another recipe changes, it won't rerun.
  d) If you change some global configuration variable or shared .bbclass
     it will rebuild.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>