package_rpm: Set _tmppath to avoid races over tmp files
Occasionally we keep seeing "unable to open temp file" messages during
do_package_write_rpm tasks. This appears to happen when multiple
processes are writing rpm files and is likely due to using the
shared system temp directory. This patch changes the tmp path
to the package work directory meaning conflicts should become
a non-issue.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
