VPPAPIGEN: use SOURCE_DATE_EPOCH for datestring
pointed me that:
For reproducible builds datestring should be generated using
SOURCE_DATE_EPOCH which distributions set centrally, and have build
tools that consume it to produce reproducible output.
# C generation
import datetime
import os
+import time
-datestring = datetime.datetime.now()
+datestring = datetime.datetime.utcfromtimestamp(int(os.environ.get('SOURCE_DATE_EPOCH', time.time())))
input_filename = 'inputfil'
top_boilerplate = '''\
/*
