package_tar.bbclass: Sync to the other package_* classes

Sync up the anonymous python definition with the other package_*.bbclass
files.  This should make future maintenance easier, even though it has
no difference in behavior from what was there.

Additional, there was a missing deltask in the nopackages.bbclass related
to the package_tar which has been corrected.  This could cause problems on
native recipes when package_tar was enabled.

Signed-off-by: Mark Hatle <mark.hatle@kernel.crashing.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>