To avoid races between the sstate tasks/hooks using ${B} as the cwd, and other
tasks such as cmake_do_configure which deletes and re-creates ${B}, ensure that
all sstate hooks are run in the right directory, and run the prefunc/postfunc in WORKDIR.
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>