+ocamlnet.3.7.4-1

Backport "protocol robustness: omitting the port number from the Host
header when it is equal to the protocol-dependent default port"
https://godirepo.camlcity.org/svn/lib-ocamlnet2/branches/onet4@1961
Merge pull request #2474 from Chris00/master

+ocamlnet.3.7.4-1