souphttpsrc: Use proxy username/password from http_proxy

Submitted by Rajat Verma

Link to original bug (#746382)

Description

http_proxy variable may also contain proxy username & password in below format:

<protocol>://<username>:<password>@<proxy ip>:<proxy port>

souphttpsrc only sets proxy url (<proxy ip> & <proxy port>) is http_proxy variable is defined in environment but not proxy-id and proxy-pw.

Problem I am facing is "proxy authentication required 407" while testing MPEG-DASH, which plays a .mpd located outside my company network.

dashdemux, for fetching a segment, uses gst_element_make_from_uri(). Now I have no way to set proxy-id/proxy-pw on this particular souphttpsrc instance, due to which segment fetching fails.

If souphttpsrc may start parsing proxy-id/proxy-pw using below functions from soup library:
soup_uri_get_user()
soup_uri_get_password()
then my issue would be resolved.