sha256 problem encountered during 'make release'

[James E Keenan]

In the course of preparing the 3.7 release, Coke++ reported being unable 
to do 'make release' on Mac OS X due to the requirement to create sha256 
checksums of the release tarballs.

I have been attempting to remedy this problem in the tar_shasum branch. 
  I added entries for 'tar' and 'sha256sum' to init::defaults, then 
provided OS-specific values to override the default (Linux) setting for 
'sha256sum' as I could find them for Darwin, FreeBSD and OpenBSD in 
their respective init::hints::* packages.  (I could not locate ways to 
create sha256 checksums on NetBSD or DragonFlyBSD.  I have not yet 
explored how to do so on Windows.)

(It's interesting that the utility suggested by dukeleto++ for Darwin, 
'shasum -a 256' is a command-line utility bundled with Darwin that is 
actually implemented in Perl 5!)

Using the code in this branch, I have successfully run:

   perl Configure.pl && make relcheck

... on Linux and Darwin, which constitute proof of the solution's 
validity.  Coke, can you confirm this?

Also, can anyone provide the Windows equivalent?

Thank you very much.

kid51