Both Win64 ABI and System V ABI clearly state that 16-byte stack
alignment is required _before_ the call, not after.
Added some additional details about the Win64 ABI, including a mention
of "shadow space", which is one of the less intuitive aspects.
Make the source code for the documentation a little easier to deal
with by breaking it into individual chapter files. Add support to
rdsrc.pl for auto-generating dependencies.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>