Replaced calls to swrite with Curl_write_plain and calls to sread
with Curl_read_plain.

With some committer adjustments

Make the Schannel implementation use libcurl's default buffer size
for the initial received encrypted and decrypted data cache buffers.
The implementation still needs to handle more data since more data
might have already been received or decrypted during the handshake
or a read operation which needs to be cached for the next read.

curl_schannel.c - implemented graceful SSL shutdown.  If we fail to
shutdown the connection gracefully, I've seen schannel try to use a
session ID for future connects and the server aborts the connection
during the handshake.

curl_schannel.c - auto certificate validation doesn't seem to work
right on CE.  I added a method to perform the certificate validation
which uses CertGetCertificateChain and manually handles the result.

Added helper methods InitSecBuffer() and InitSecBufferDesc() to make it
easier to set up SecBuffer & SecBufferDesc structs.

Avoid usage of some MS type synonyms to allow compilation with
compiler headers that don't define these, using simpler synonyms.

Coverity actually pointed out flawed logic in the previous call to
Curl_strntoupper() where the code used sizeof() of a pointer to pass in
a size argument. That code still worked since it only needed to
uppercase 4 letters. Still, the entire malloc/uppercase/free sequence
was pointless since the code has already matched the string once in the
condition that starts the block of code.

As spotted by Coverity, va_end() was not used previously. To make it
used I took away a bunch of return statements and made them into
assignments instead.

SSPI related code now compiles with ANSI and WCHAR versions of security
methods (WinCE requires WCHAR versions of methods).

Pulled UTF8 to WCHAR conversion methods out of idn_win32.c into their own file.

curl_sasl.c - include curl_memory.h to use correct memory functions.

getenv.c and telnet.c - WinCE compatibility fix

With some committer adjustments

As per request on mailing list: http://curl.haxx.se/mail/lib-2012-06/0222.html

The changes introduced in commit 2bfa57bc are not enough
to make it actually possible to use the USE_WINSSL option.
Makefile.vc was not updated and the configuration name which is
used in the build path did not match between both build files.

This patch fixes those issues and introduces the following changes:

- Replaced the -schannel name with -winssl in order to be consistent
with the other options
- Added ENABLE_WINSSL option to winbuild/Makefile.vc (default yes)
- Changed winbuild/MakefileBuild.vc to set USE_WINSSL to true if
USE_SSL is false and USE_WINSSL was not specified as a parameter
- Separated WINSSL handling from SSPI handling to be consistent with
the other options and their corresponding code path

Calls to failf() are not supposed to provide trailing newline.
Calls to infof() must provide trailing newline.

Fixed 30 or so strings.

Building with CyaSSL failed compilation. Reason being that OCSP_REQUEST and
OCSP_RESPONSE are enum values in CyaSSL and defines in <wincrypt.h> included
via <winldap.h> in ldap.c.

http://curl.haxx.se/mail/lib-2012-06/0196.html

In order to use Windows native SSL support define 'USE_WINSSL'

This option may be used to build curl/libcurl using SSL/TLS support provided
by MS windows system libraries. Option is mutually exclusive with any other
SSL library. Default value is --without-winssl.

--with-winssl option implies --with-sspi option.

Option meaningful only for Windows builds.

This is more descriptive for the user who might
not even know what schannnel is at all.

Version number is removed in order to make this info consistent with
how we do it with other MS and Linux system libraries for which we don't
provide this info.

Identifier changed from 'WinSSPI' to 'schannel' given that this is the
actual provider of the SSL/TLS support. libcurl can still be built with
SSPI and without SCHANNEL support.

No need to check if 'entry' is non-NULL in a spot where it is already checked
and guaranteed to be non-NULL.

(Spotted by a Coverity scan)

Remove two states from the enum and the corresponding code for them as
these states were never reached or used.

(Spotted by a Coverity scan)

This reverts commit 9c94236e.

It didn't server its purpose, so lets go back to long-time working code.

Removed obsolete minor status variable and parameter of status function
which was never used or set at all. Also Curl_sspi_strerror does support
only one status and there is no need for a second sub status.