MEDIUM: h1-htx: Adapt H1 data parsing to copy wrapping data in one call

MEDIUM: h1-htx: Adapt H1 data parsing to copy wrapping data in one call

Since the beginning, wrapping input data are parsed and copied in 2 steps to
not deal with the wrapping in H1 parsing functions. But there is no reason
to do so. This needs 2 calls to parsing functions. This also means, most of
time, when the input buffer does not wrap, there is an extra call for
nothing.

Thus, now, the data parsing functions try to copy as much data as possible,
handling wrapping buffer if necessary.