Ensure that the copy of the CURLOPT_INTERFACE string is freed if we
decide we can reuse an existing connection.

This is the same fix applied for the conditional code that uses select()
that was already done for the poll specific code in commit
b61e8b81.

We found a problem with ftp transfer using libcurl (7.23 and 7.25)
inside an application which is receiving unix signals (SIGUSR1,
SIGUSR2...) almost continuously. (Linux 2.4, PowerPC, HAVE_POLL_FINE
defined).

Curl_socket_check() uses poll() to wait for the socket, and retries it
when a signal is received (EINTR). However, if a signal is received and
it also happens that the timeout has been reached, Curl_socket_check()
returns -1 instead of 0 (indicating an error instead of a timeout).

In our case, the result is an aborted connection even before the ftp
banner is received from the server, and a return value of
CURLE_OUT_OF_MEMORY from curl_easy_perform() (Curl_pp_multi_statemach(),
in pingpong.c, actually returns OOM if Curl_socket_check() fails :-)
Funny to debug on a system on which OOM is a possible cause).

Bug: http://curl.haxx.se/mail/lib-2012-07/0122.html

bug #3544688 "crash during retry with libcurl and SFTP"

Due to WSAPoll bugs, libcurl does not work as intended. When the cURL
library is used to setup a connection to an incorrect port, normally the
result is CURLE_COULDNT_CONNECT, /* 7 */, but due to the bug in WSAPoll,
the result now is CURLE_OPERATION_TIMEDOUT, /* 28 - the timeout time was
reached */.

On August 1, Jan Koen Annot opened a case for this to Microsoft Premier
Online (https://premier.microsoft.com/).  The support engineer handling
the case wrote that the case description is quite clear.  He will try to
reproduce the issue and then proceed with troubleshooting it.

Reported by: Jan Koen Annot
Bug: http://curl.haxx.se/mail/lib-2012-07/0310.html

When figuring out if the data stream needs to be rewound when the
request is to be resent, we must not access the HTTP struct unless the
protocol used is indeed HTTP...

Bug: http://curl.haxx.se/bug/view.cgi?id=3544688

Braces, not parentheses, should be used for shell variable names.

Bug: http://curl.haxx.se/bug/view.cgi?id=3551460
Reported by: Edward Sheldrake

This fixes a build failure of lib/ssluse.c.

Bug: http://curl.haxx.se/bug/view.cgi?id=3552997

Stupid lack of range checks caused the code to overwrite local variables
after glob number nine. Added checks now.

Bug: http://curl.haxx.se/bug/view.cgi?id=3546353

Fix a bug where closed sockets (fd -1) were left in the all_sockets
list, because of missing parens in a pointer arithmetic expression

Reenable the tests that were locking up due to this bug.

Two separate "Value stored to 'XXX' is never read" warnings

Value stored to 'separator' is never read

Bug: http://curl.haxx.se/bug/view.cgi?id=3554668
Reported by: Anthony G. Basile

Bug: http://curl.haxx.se/bug/view.cgi?id=3554668
Reported by: Anthony G. Basile

The tests 2025, 2028 and 2031 don't work for me so I'll have them
disabled for now until we solve the problem.

SO_KEEPALIVE flag to all sockets. Note that several loops which used to continue on a return value
of 0 (theoretical since 0 would never be returned without O_NONBLOCK) now break on 0 so that they
won't continue reading until after poll is called again.

for non-blocking sockets: now -1 means error or connection finished, 1 means data was read, and 0
means there is no data available now so need to wait for poll (new return value)

half-finished.

Note the the req struct used to be re-initialized AFTER reading pipeline data, so now that we
initialize it from the caller we must be careful not to overwrite the pipeline data.

Also we now need to handle the case where the buffer is already full when get_request is called -
previously this never happened as it was always called with an empty buffer and looped until done.

Now get_request is called in a loop, so the next step is to run the loop on a socket only when poll
signals it is readable.

The next step will be to call the correct function after a poll, rather than looping unconditionally

be redundant once we poll

It eliminates noisy events when using inotify and fixes a TOCTOU issue.

Bug: https://bugzilla.redhat.com/844385

Discussion on the list: http://curl.haxx.se/mail/lib-2012-07/0271.html

Removed APOP and SASL authentication from the POP3 section and metalink
support from the client section as these features were implemented in
this release.

Moved adding gssapi to SASL into it's own section rather than repeat it
for each protocol.

Let's call it 7.27.1 for now, but it it probably going to become 7.28.0
when released.