classes/populate_sdk_base: fix race condition with do_rootfs
do_rootfs has ${S} in cleandirs, and during do_populate_sdk we call
exec_func() several times, which by default uses ${B} as the working
directory. If do_populate_sysroot and do_rootfs race against eachother,
the directory may not exist at the exact instant that the setup code
for do_populate_sdk tries to cd into it. We don't actually use ${B}
for do_populate_sysroot so we can set it to something else just for that
task to avoid the race.
NOTE: because this task name contains an underscore, the override will
not work; the BitBake patch that changes these to hyphens for the
task override is required for this patch to work (but won't break things
without it.)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
