user agent patch src/port1.0/portfetch.tcl

[brad@…]

Found --user-agent arg in curl.c but no way to use it within a Portfile.

This patch is for src/port1.0/portfetch.tcl to allow setting new fetch.user_agent var in Portfiles.

With this patch I was able to get around the fetch issues with the new port skrooge. #27865

The skrooge server didn't like our user agent header.
With this patch I add the following to Portfile and fetch succeeds:

fetch.user_agent "Mozilla/4.0"

[ryandesign@…]

I'm not convinced we want to allow portfiles to specify the curl useragent. Servers that disallow our useragent to download files are pretty broken and should be fixed.