Drop the icecc class and related variables

Dropped by commit ecf8c386cf83 ("classes/recipes-devtools: Drop icecc
from OE-Core") in OE-Core.

Remove documentation for the class and the related variables. Remove the
references to this class.

(From yocto-docs rev: 30c9413c5106bcbcc1600ef16b8d0cece86d8158)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/ref-manual/classes.rst

@@ -1143,80 +1143,6 @@ The :ref:`ref-classes-gzipnative` class enables the use of different native vers
 ``gzip`` and ``pigz`` rather than the versions of these tools from the
 build host.
 
-.. _ref-classes-icecc:
-
-``icecc``
-=========
-
-The :ref:`ref-classes-icecc` class supports
-`Icecream <https://github.com/icecc/icecream>`__, which facilitates
-taking compile jobs and distributing them among remote machines.
-
-The class stages directories with symlinks from ``gcc`` and ``g++`` to
-``icecc``, for both native and cross compilers. Depending on each
-configure or compile, the OpenEmbedded build system adds the directories
-at the head of the ``PATH`` list and then sets the ``ICECC_CXX`` and
-``ICECC_CC`` variables, which are the paths to the ``g++`` and ``gcc``
-compilers, respectively.
-
-For the cross compiler, the class creates a ``tar.gz`` file that
-contains the Yocto Project toolchain and sets ``ICECC_VERSION``, which
-is the version of the cross-compiler used in the cross-development
-toolchain, accordingly.
-
-The class handles all three different compile stages (i.e native,
-cross-kernel and target) and creates the necessary environment
-``tar.gz`` file to be used by the remote machines. The class also
-supports SDK generation.
-
-If :term:`ICECC_PATH` is not set in your
-``local.conf`` file, then the class tries to locate the ``icecc`` binary
-using ``which``. If :term:`ICECC_ENV_EXEC` is set
-in your ``local.conf`` file, the variable should point to the
-``icecc-create-env`` script provided by the user. If you do not point to
-a user-provided script, the build system uses the default script
-provided by the recipe :oe_git:`icecc-create-env_0.1.bb
-</openembedded-core/tree/meta/recipes-devtools/icecc-create-env/icecc-create-env_0.1.bb>`.
-
-.. note::
-
-   This script is a modified version and not the one that comes with
-   ``icecream``.
-
-If you do not want the Icecream distributed compile support to apply to
-specific recipes or classes, you can ask them to be ignored by Icecream
-by listing the recipes and classes using the
-:term:`ICECC_RECIPE_DISABLE` and
-:term:`ICECC_CLASS_DISABLE` variables,
-respectively, in your ``local.conf`` file. Doing so causes the
-OpenEmbedded build system to handle these compilations locally.
-
-Additionally, you can list recipes using the
-:term:`ICECC_RECIPE_ENABLE` variable in
-your ``local.conf`` file to force ``icecc`` to be enabled for recipes
-using an empty :term:`PARALLEL_MAKE` variable.
-
-Inheriting the :ref:`ref-classes-icecc` class changes all sstate signatures.
-Consequently, if a development team has a dedicated build system that
-populates :term:`SSTATE_MIRRORS` and they want to
-reuse sstate from :term:`SSTATE_MIRRORS`, then all developers and the build
-system need to either inherit the :ref:`ref-classes-icecc` class or nobody should.
-
-At the distribution level, you can inherit the :ref:`ref-classes-icecc` class to be
-sure that all builders start with the same sstate signatures. After
-inheriting the class, you can then disable the feature by setting the
-:term:`ICECC_DISABLED` variable to "1" as follows::
-
-   INHERIT_DISTRO:append = " icecc"
-   ICECC_DISABLED ??= "1"
-
-This practice
-makes sure everyone is using the same signatures but also requires
-individuals that do want to use Icecream to enable the feature
-individually as follows in your ``local.conf`` file::
-
-   ICECC_DISABLED = ""
-
 .. _ref-classes-image:
 
 ``image``