Added CURLOPT_HTTP09_ALLOWED and --http0.9 for this purpose.
For now, both the tool and library allow HTTP/0.9 by default.
docs/DEPRECATE.md lays out the plan for when to reverse that default: 6
months after the 7.64.0 release. The options are added already now so
that applications/scripts can start using them already now.
Fixes#2873Closes#3383
HTTP 1.1 is clearly specified to only allow three digit response codes,
and libcurl used sscanf("%3d") for that purpose. This made libcurl
support smaller numbers but not larger. It does now, but we will not
make any specific promises nor document this further since it is going
outside of what HTTP is.
Bug: http://curl.haxx.se/bug/view.cgi?id=1441
Reported-by: Balaji