[BUG:#20329] If-Modified-Since support

[vinothkumar raman]

Hi all,

We need to give out the time stamp the local file in the Request
header for that we need to pass on the local file's time stamp from
http_loop() to get_http() . The only way to pass on this without
altering the signature of the function is to add a field to struct url
in url.h

Could we go for it?

Thanks,
VinothKumar.R