[PATCH cygport] Set TZ=UTC if SOURCE_DATE_EPOCH is used

[Christian Franke]

Christian Franke wrote:
> Further tests of 'repro-check' patch revealed that the "origsrc/*" 
> timestamps in patch files contain the local timezone offset.
>

This would be no longer needed for patch files if "Modify origsrc 
timestamp in patch files if SOURCE_DATE_EPOCH is used" would be applied.

This TZ=UTC patch could possibly be dropped then.


> The attached patch is on top of the "Add more checks of 
> SOURCE_DATE_EPOCH" patch. It could also be applied independently but 
> then requires conflict resolution due to the then missing 'else' branch.
>