archiver/package_rpm: Fix the worst src.rpm generation race

archiver/package_rpm: Fix the worst src.rpm generation race

The package_rpm code is writing outside the task's sstate directory into
the sstate of do_deploy_archives. This is "out of spec" since if the
task is installed from sstate, the files are not restored. This means
the files may appear/disappear, things are not deterministic and there are
races.

Extend the do_package_write_rpm code to handle writing the src.rpm into
place to avoid these issues. There are other problems but this avoids races
around this file.

(From OE-Core rev: c6e151ba7fe0f14044537cf0ab2cac436f1496e3)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>