* Rename add_layer() to add_layers() so that add_layer_dependencies() can
  re-use it.

* Avoid adding the layer if it is already present

[YOCTO #13148]

(From OE-Core rev: b9cc18d83f55ff48c3d6e60c56359f6736d5a06a)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

yocto-check-layer will find locked-sigs.inc under builddir,
but locked-sigs.inc is generated under current bitbake working
dir. if run yocto-check-layer outside builddir, we will met error
like "No such file or directory: *locked-sigs.inc". change to
run bitbake -S under builddir to fix this problem.

[YOCTO #12973]

(From OE-Core rev: 2ec0bc0b038bc6413978c8f34ef5c0d22b4bc3e7)

Signed-off-by: Changqing Li <changqing.li@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

When Layer A and Layer B depend on each other, then we will end up in a
recursive loop in function recurse_dependencies(). To avoid such situation
before making the recursive function call we check whether or not we have
already processed this layer.

e.g. without this patch, running this script on layers with dependency loops, we are seeing:

$ yocto-check-layer -d  /srv/work/oe/meta-openembedded/
INFO: Detected layers:
INFO: meta-python: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-python
INFO: meta-filesystems: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-filesystems
INFO: meta-gnome: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-gnome
INFO: meta-xfce: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-xfce
INFO: meta-networking: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-networking
INFO: meta-initramfs: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-initramfs
INFO: meta-oe: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-oe
INFO: meta-multimedia: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-multimedia
INFO: meta-perl: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-perl
INFO: meta-webserver: LayerType.SOFTWARE, /srv/work/oe/meta-openembedded/meta-webserver
INFO:
INFO: Setting up for meta-python(LayerType.SOFTWARE), /srv/work/oe/meta-openembedded/meta-python
DEBUG: Processing dependencies core openembedded-layer for layer meta-python.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
DEBUG: Processing dependencies core networking-layer for layer meta-oe.
DEBUG: Processing dependencies core openembedded-layer meta-python for layer meta-networking.
...
...
...
[keep repeating]

This patch fixes this situation.

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

[YOCTO #12661]

Signed-off-by: Alexander Kanavin <alexander.kanavin@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

LayerError doesn't exist and will lead to an error when this failure
code path is hit.

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

Search made with the following regex: getVar ?\((.*), True\).

Signed-off-by: Ming Liu <liu.ming50@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

"Yocto Project Compatible" [1] is a programme which requires you meet
specific criteria including going through an application process - it is
not sufficient simply to run the script we have created here and have it
produce no warnings/errors. To avoid people being confused by the fact
that this script uses the term "compatible" or variations thereof,
substitute usage of that word with "check" instead. The functionality of
the script is unchanged.

[1] https://www.yoctoproject.org/ecosystem/yocto-project-branding-program

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>