package.bbclass: Set umask in populate_packages

:Release Notes:
Directory created with 777 permissions in do_install was loosing
some permissions before package was created, it was caused by
using os.mkdir(path, permissions) where permissions are changed
based on system umask.

:Detailed Notes:
Only modification from oe-core/dylan is this change:
http://git.openembedded.org/openembedded-core/commit/?id=f91226553e39439bfd17ab2b06c56cb8bf41061b

:Testing Performed:
Directories have correct permissions now.

:QA Notes:
Permissions on some directories are expected to be changed, but
it shouldn't change any functionality.

:Issues Addressed:
[GF-34330] Can't write to /media/internal from inside a jail

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>
Change-Id: I6e6921a9bb1d3c57025cffe2e6fc32897b5f10f5
Reviewed-on: https://g2g.palm.com/3489
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>