All plain C examples now (mostly) adhere to the curl code style. While
they are only examples, they had diverted so much and contained all
sorts of different mixed code styles by now. Having them use a unified
style helps users and readability. Also, as they get copy-and-pasted
widely by users, making sure they're clean and nice is a good idea.

573 checksrc warnings were addressed.

cleaning up handles is a good idea as we leak memory otherwise

Also, line wrapped before 80 columns.

It is wasteful to search it backwards if we look for _any_ slash.

We only care if at least one cipher-suite is enabled, so it does
not make any sense to iterate till the end and count all enabled
cipher-suites.

Closes #626

Since we didn't keep the input argument around after having called
mbedtls, it could end up accessing the wrong memory when figuring out
the ALPN protocols.

Closes #642

For example something like --output \\?\C:\foo

As of https://boringssl-review.googlesource.com/#/c/6980/, almost all of
BoringSSL #ifdefs in cURL should be unnecessary:

- BoringSSL provides no-op stubs for compatibility which replaces most
  #ifdefs.

- DES_set_odd_parity has been in BoringSSL for nearly a year now. Remove
  the compatibility codepath.

- With a small tweak to an extend_key_56_to_64 call, the NTLM code
  builds fine.

- Switch OCSP-related #ifdefs to the more generally useful
  OPENSSL_NO_OCSP.

The only #ifdefs which remain are Curl_ossl_version and the #undefs to
work around OpenSSL and wincrypt.h name conflicts. (BoringSSL leaves
that to the consumer. The in-header workaround makes things sensitive to
include order.)

This change errs on the side of removing conditionals despite many of
the restored codepaths being no-ops. (BoringSSL generally adds no-op
compatibility stubs when possible. OPENSSL_VERSION_NUMBER #ifdefs are
bad enough!)

Closes #640

Allow --output to reserved dos device names without the device prefix
for backwards compatibility.

Example: --output NUL can be used instead of --output \\.\NUL

Bug: https://github.com/curl/curl/commit/4520534#commitcomment-15954863
Reported-by: Gisle Vanem

It turns out Firefox and Chrome both allow spaces in cookie names and
there are sites out there using that.

Turned out the code meant to strip off trailing space from cookie names
didn't work. Fixed now.

Test case 8 modified to verify both these changes.

Closes #639

When trying to verify a peer without having any root CA certificates
set, this makes libcurl use the TLS library's built in default as
fallback.

Closes #569

RFC 7230 says we should stop. Firefox already stopped.

Bug: https://github.com/curl/curl/issues/633
Reported-By: Brad Fitzpatrick

Closes #633

... as we're HTTPS on the main site now, there's no point in that
extra step

Extract the filename from the last slash or backslash. Prior to this
change backslashes could be part of the filename.

This change needed for the curl tool built for Cygwin. Refer to the
CYGWIN addendum in advisory 20160127B.

Bug: https://curl.haxx.se/docs/adv_20160127B.html

sk_X509_EXTENSION_num may return an unsigned integer, however the value
will fit in an int.

Bug: https://github.com/curl/curl/commit/dd1b44c#commitcomment-15913896
Reported-by: Gisle Vanem

.. also fix a conversion bug in the unused function
curl_win32_ascii_to_idn().

And remove wprintfs on error (Jay).

Bug: https://github.com/curl/curl/pull/637

closesocket => close_socket
Winsock already has the former.

Bug: https://curl.haxx.se/mail/lib-2016-02/0016.html

Bug: https://curl.haxx.se/mail/lib-2016-02/0017.html

... done on request and as it is a fair point.

- Add unit test 1604 to test the sanitize_file_name function.

- Use -DCURL_STATICLIB when building libcurltool for unit testing.

- Better detection of reserved DOS device names.

- New flags to modify sanitize behavior:

SANITIZE_ALLOW_COLONS: Allow colons
SANITIZE_ALLOW_PATH: Allow path separators and colons
SANITIZE_ALLOW_RESERVED: Allow reserved device names
SANITIZE_ALLOW_TRUNCATE: Allow truncating a long filename

- Restore sanitization of banned characters from user-specified outfile.

Prior to this commit sanitization of a user-specified outfile was
temporarily disabled in 2b6dadc5 because there was no way to allow path
separators and colons through while replacing other banned characters.
Now in such a case we call the sanitize function with
SANITIZE_ALLOW_PATH which allows path separators and colons to pass
through.


Closes https://github.com/curl/curl/issues/624
Reported-by: Octavio Schroeder

Free an existing domain before replacing it.

Bug: https://github.com/curl/curl/issues/635


Reported-by:  <silveja1@users.noreply.github.com>

Closes #632