classes/package: record PKGSIZE as total file size in pkgdata

classes/package: record PKGSIZE as total file size in pkgdata

We were using "du -sk" to collect the total size of all files in each
package for writing out to PKGSIZE in each pkgdata file; however this
reports the total space used on disk not the total size of all files,
which means it is dependent on the block size and filesystem being used
for TMPDIR on the build host. Instead, take the total of the size
reported by lstat() for each packaged file, which we are already
collecting for FILES_INFO in any case.

Note: this changes PKGSIZE to be reported in bytes instead of kilobytes
since this is what lstat reports, but this is really what we should be
storing anyway so that we have the precision if we need it.

Fixes [YOCTO #5334]

(From OE-Core rev: 29615b36fca696822a715ece2afbe0bf9a43ed61)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>