[yocto] The BitBake equivalent of "Hello, World!"

[Patrick Turley]

In my previous message, some of the indentation in the representation of
my file tree was wrong (because we're using Outlook, which destroy all
indentation when you paste it into an e-mail message). The errors are
small, but I want to avoid annoying anyone who might think I don't even
have the file tree constructed correctly.

The following is accurate:

>/home/pturley/Workspace/woohoo
>    |
>    +-- build
>    |   |
>    |   +-- classes
>    |   |   |
>    |   |   +-- base.bbclass
>    |   |
>    |   |     +-------------------------------------------
>    |   |     | do_hello() {
>    |   |     |     echo Hello
>    |   |     | }
>    |   |     |
>    |   |     | addtask hello
>    |   |     +-------------------------------------------
>    |   |
>    |   +-- conf
>    |       |
>    |       +-- bblayers.conf
>    |       |
>    |       | +-------------------------------------------
>    |       | | BBLAYERS ?= " \
>    |       | |   /home/pturley/Workspace/woohoo/LayerA \
>    |       | |   "
>    |       | +-------------------------------------------
>    |       |
>    |       +-- bitbake.conf
>    |
>    |         +-------------------------------------------
>    |         | CACHE = "${TOPDIR}/cache"
>    |         +-------------------------------------------
>    |
>    +-- LayerA
>    |   |
>    |   +-- a.bb
>    |   |
>    |   |     +-------------------------------------------
>    |   |     | PN = 'a'
>    |   |     | PV = '1'
>    |   |     +-------------------------------------------
>    |   |
>    |   +-- conf
>    |       |
>    |       +-- layer.conf
>    |
>    |         +-------------------------------------------
>    |         | BBPATH .= ":${LAYERDIR}"
>    |         | BBFILES += "${LAYERDIR}/*.bb"
>    |         +-------------------------------------------
>    |
>    +-- BitBake ...
>
>    The BitBake directory origin is:
>
>        http://git.openembedded.org/bitbake/
>
>    I have the 1.15.2 tag checked out, which is what
>    Yocto denzil uses.