corrections

I also replaced all printf() calls with calls to Curl_failf()

platforms that have such a function.
This affects multi-thread running libcurls on IPv4 systems that have VERBOSE
switched on. The previous version was risking that another thread overwrote
the data before it was read out in this thread. There could possibly also
be a slight risk that the data isn't zero terminated for a short while and
thus could cause the thread to crash...

header directory but the function *is* present!

to become properly 8-byte aligned on 64-bit archs. Philip Gladstone reported.

headers.

stopped working after the dec-20 fixes that now supports FTP operations to
skip the transfer phase.

"3.9 How do I use curl in my favourite programming language?"

we return a set of headers not more. This enables FTP operations that don't
transfer any data, only perform FTP commands.