go.bbclass: add do_unpack function to handle common cases
Go source trees have a particular structure, with all
sources located under ${GOROOT}/src/<import-path>.
The fetcher step implemented by the 'go get' command
automatically follows this structure, so we need
to do the same here.
Since most Go packages are hosted in git repositories,
this adds a custom do_unpack() function that sets
the destsuffix to match the expected directory structure,
for any git SRC_URIs that haven't had a destsuffix
explicitly set in the recipe.
This simplifies recipe writing for the most common
cases.
Signed-off-by: Matt Madison <matt@madison.systems> Signed-off-by: Otavio Salvador <otavio@ossystems.com.br> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
