Waf requires that the current working directory be ${S} (the location of
the wscript) when building. Most of the time, this was true only because
B defaults to S. However, anything that changed that behavior (notably,
using externalsrc) would break the recipe. Remedy this by explicitly
changing cwd to ${S} when running waf commands. As a happy side effect,
B can be set up for "out of tree" builds to keep the source directory
clean.
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
