allarch: Always inhibit default dependencies and set empty TARGET_PREFIX

* typical case where we inherit allarch and override PACKAGE_ARCH
  are packagegroup recipes, but those need default dependencies
  inhibited even when they are MACHINE_ARCH or TUNE_PKGARCH.
  I don't know about any recipe which inherits allarch and needs
  default dependencies.
* set empty TARGET_PREFIX
  This has a bit weird reason caused by unsupported setup where
  external-toolchain is used in some DISTRO only for some MACHINEs
  and internal is used for other MACHINEs.
  Because external-toolchain usually comes with different TARGET_PREFIX
  it was causing allarch recipes to have different signatures even
  when they don't use toolchain at all.
  Empty TARGET_PREFIX also helps to find allarch recipes which still
  have default dependency on e.g. virtual/${TARGET_PREFIX}gcc.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
xuser-account: Drop allarch inherit

* has build time dependency on TUNE_PKGARCH recipes:
  bitbake-diffsigs sstate-diff/1383303628/*/all*/xuser-account/*do_configure*
  Hash for dependent task base-passwd_3.5.26.bb.do_populate_sysroot changed from 09b3168865b6212269d4e5512a963b9e to ffa22dc51e42a164a7392ec719151629
  Hash for dependent task shadow_4.1.4.3.bb.do_populate_sysroot changed from f426f0c93b2d341050b2547804645314 to 89bdbb151f8c200553c9a74e89504457
  Hash for dependent task shadow-sysroot_4.1.4.3.bb.do_populate_sysroot changed from c42103fe54ac5109eab8de4fb0eb9a75 to f83f628e766fdbd49eb2a44cf6134339

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
linux-firmware: Drop allarch

* the recipe itself is allarch, but update-alternatives adds dependency on
  virtual/${MLPREFIX}update-alternatives which can be TUNE_PKGARCH opkg
  causing linux-firmware signature to be different for different TUNE_PKGARCHs
  Hash for dependent task opkg_svn.bb.do_populate_sysroot changed from 8d215059308161841a84542dd1dcbf3a to 80b280c741c392cf5b30dd67b61dd56e

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
ppp-dialin: Drop allarch

* depends on some TUNE_PKGARCH recipes:
  base-passwd, ppp_, shadow-sysroot, shadow

  Hash for dependent task base-passwd_3.5.26.bb.do_populate_sysroot changed from ff08f0198f5424a21ccb61957325ffdf to d9d962e2d8c0d591b916ed68aa826efe
  Hash for dependent task ppp_2.4.5.bb.do_populate_sysroot changed from 515251fb9d5196733f9b6ca0f6cc041b to 5cfb0b7b71f4440c3147da52c22234cc
  Hash for dependent task shadow-sysroot_4.1.4.3.bb.do_populate_sysroot changed from 3e5bddc578887636c1809e4cdf28c1c2 to 8f03231a1d4bb1aea6c4adce1febc1b4
  Hash for dependent task shadow_4.1.4.3.bb.do_populate_sysroot changed from 518f7edcba3545e5c60c3a13cef23169 to 7dbf1646de02a117bf0d573276b878c0

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
initramfs-framework: Drop allarch

* depends on TUNE_PKGARCH busybox and udev
  Hash for dependent task busybox_1.20.2.bb.do_packagedata changed from b814437371de0c3253bdd3610c051f30 to 7dd9c851d5f7c675dd65cc7872c30743
  Hash for dependent task udev_182.bb.do_packagedata changed from 1034300ce0e27d444e0e7d9e2a239605 to c13031b26b2a86dcf9bcce33b7823477

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
resolvconf: Drop allarch

* has runtime dependency on TUNE_PKGARCH bash
  Hash for dependent task bash_4.2.bb.do_packagedata changed from d6eafb155c37bc2da7327492afa449fb to 0ae080aaa92025af690cf16ef0cd2b7e

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
gtk+: Add PACKAGECONFIG for directfb

* building without x11 doesn't work, because it sets default
  gdkbackend to x11 and then requires cairo-xlib to be available
* checking for CAIRO_BACKEND... no
  configure: error: Package requirements (cairo-xlib >= 1.6) were not met:

  No package 'cairo-xlib' found

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
python: explicitly disable bluetooth.h check

* bluetooth.h is autodetected from sysroot and influences 2 python files:
  /usr/include/python2.7/pyconfig-32.h
  /usr/lib/python2.7/lib-dynload/_socket.so
* it doesn't link with bluez, so it wasn't detected by
  test-dependencies.sh, but still causes undeterministic builds and
  should be fixed
* we can use PACKAGECONFIG, but I don't expect many people to use bt
  support in python-socket

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
qemux86: Add identical qemux86copy variant for tests

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
sstate-diff-machines.sh: Return non-zero return code when there was some failure detected

* add --analyze option, which is useful when using from jenkins job
  where you don't want to read output just to dectect how bad it was
* I was always using something like this inside jenkins job, but better
  to share it in original script

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
test-dependencies.sh: Return non-zero return code when there was some failure detected

* this is useful when using from jenkins job where you don't want to read
  output just to dectect how bad it was
* add .log suffix to all files, so they can be easily downloaded from
  http servers without default mimetype set to something useful
* add recipes failed in step 1 to steps 2 and 3 to generate standalone
  logs for them

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