Redo the calculation of the alignment and placement of static TLS data to

Redo the calculation of the alignment and placement of static TLS data to
correctly take into account the segment p_align.  Previously, anything
with a size belong the natural alignment or with alignment larger than
the natural one would either not be intialized correctly, be misaligned,
or result in the TIB being misaligned.

Problems reported by Charles Collicutt (charles (at) collicutt.co.uk)
ok kettenis@