[PATCH cygport] Add initial support for SOURCE_DATE_EPOCH

[Brian Inglis]

On 2023-08-23 11:39, Christian Franke via Cygwin-apps wrote:
> A small step towards reproducible packaging...
> 
> Currently only tested with upcoming smartmontools package - contains only exe, 
> man, doc files (no dll, lib, ...). Multiple cygport runs produce binary 
> identical distribution tarballs if SOURCE_DATE_EPOCH (from the past) is 
> specified in the cygport file.

What format is this variable?
Would be best to use some ISO format e.g.

	%Y-%m-%dT%H:%M:%SZ	or
	%Y-%m-%dT%H:%M:%S	[local]

that is human readable and can be used by all POSIX command options
[e.g. see touch(1p) -d] that accept date-time stamps.

Could do with docs and NEWS entries for new variables, otherwise packagers do 
not know it exists, and how to use it e.g.

#****f* Information/BUILD_REQUIRES
#  SYNOPSIS
#  BUILD_REQUIRES="ATOM [ATOM] ..."
#  DESCRIPTION
#  A single-line strings containing a list of packages on which this source
#  package depends at build-time. This will be added to the build-depends:
#  field of the auto-generated -src.hint file.
#  NOTES
#  * Unlike REQUIRES, there is no auto-detection of build-time requirements.
#  * Any newlines in this variable must be escaped.
#  * Unlike the deprecated DEPEND variable, only actual package names, or
#    atoms that are listed PROVIDES of other packages, may be used in this
#    variable.
#****

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry