The net/http package has long documented that Request.ProtoMajor and
Request.ProtoMinor are ignored for outgoing requests (HTTP/1.1 or
HTTP/2 is always used, never HTTP/1.0). There was one part in the code
that was actually checking 1.0 vs 1.1, but it appears to have been
harmless. Remove it.

Fixes #18407

Change-Id: I362ed6c47ca2de7a2fbca917ed3e866273cfe41f
Reviewed-on: https://go-review.googlesource.com/45155
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>