Reduce padding in often-used structs

Reduce the padding in some often-used structs for 64bit machines.
32bit machines should also profit from most changes, but to a
lesser degree.

Change-Id: Ic4c67b94e962731de4f31164c52a372d78944ccc
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>