Name the pre-built docs tarball on the remote machine according to the
release script name so that multiple tarballs going to a single remote
machine do not clobber one another.
Avoid requiring all build machines for the upstream packaging process to
have Python and Sphinx installed. Instead create a way to build the
documentation once on the host machine and copy it to each build machine
as a tarball with content to include in the installation tree for
packaging.
Only temporarily until we can setup a new cygwin build machine
for making releases. It's specific to the script that runs on
dash2win64 anyhow. When we add a new script to run it on a
different machine, and stop building the cygwin releases on
dash2win64, this change will naturally no longer apply.
Set GIT_COMMAND to "git" -- each machine involved in building
the CMake release binaries has the right "git" in the PATH.
Separate the release scripts into two batches so we can build
multiple releases on the same machine, in serial, if necessary.
We currnetly do this with the Windows and Cygwin release
binaries on dash2win64.
Sort the files to be uploaded, so that sorting them by modification
time (file copy / upload time) is equivalent to sorting them
alphabetically.
