MINOR: h1-htx: Reports non-HTTP version via dedicated flags

MINOR: h1-htx: Reports non-HTTP version via dedicated flags

Now, when the HTTP version format is not strictly valid, flags are set on
the h1 parser and the HTX start-line. H1_MF_NOT_HTTP is set on the H1 parser
and HTX_SL_F_NOT_HTTP is set on the HTX start-line. These flags were
introduced to avoid parsing again and again the version to know if it is a
valid version or not, escpecially because it is most of time valid.