Reverting the changes of 5e37082e to marshall.h and osdep.h

The following commit incorrectly changed the way 64-bit integers are
marshalled:

commit 5e37082e
Author: sponcec3 <Sebastien.Ponce@cern.ch>
Date:   Wed Jan 15 15:01:19 2014 +0100

    Fixed compilation in -O2 mode.
    This in particular includes fixing the remaining strict-aliasing issues.

This commit reverts the changes that effected the marshalling of 64-bit
integers.