Just internal stuff...

Curl_safefree is now a macro defined in memdebug.h instead of a function
prototyped in url.h and implemented in url.c, so inclusion of url.h is no
longer required in order to simply use Curl_safefree.

Provide definition of macro WHILE_FALSE in setup_once.h in order to allow
other macros such as DEBUGF and DEBUGASSERT, and code using it, to compile
without 'conditional expression is constant' warnings.

The WHILE_FALSE stuff fixes 150+ MSVC compiler warnings.

Ensure existing logic in Curl_resolv_timeout() is not subverted upon getting a
negative timeout from resolve_server(). The timeout in resolve_server() could
be checked to avoid calling Curl_resolv_timeout() with an expired timeout, but
fixing this in this way allows existing logic in resolve_server() to be kept
unchanged.

follow-up for commit d20408e8

Regenerate curl's tests client knownhosts file also when, somehow,
this file is empty.

Regenerate curl's tests host and client key files also when, somehow,
any of these files are empty.

follow-up for commit c06de200

This removes command length restrictions on calling functions.

First:

File curl_ntlm.h renamed curl_ntlm_msgs.h
File curl_ntlm.c renamed curl_ntlm_msgs.c

Afterwards:

File http_ntlm.c renamed curl_ntlm.c
File http_ntlm.h renamed curl_ntlm.h

Configure script option --enable-wb-ntlm-auth renamed to --enable-ntlm-wb
Configure script option --disable-wb-ntlm-auth renamed to --disable-ntlm-wb

Preprocessor symbol WINBIND_NTLM_AUTH_ENABLED renamed to NTLM_WB_ENABLED
Preprocessor symbol WINBIND_NTLM_AUTH_FILE renamed to NTLM_WB_FILE

Test harness env var CURL_NTLM_AUTH renamed to CURL_NTLM_WB_FILE

Static function wb_ntlm_close renamed to ntlm_wb_cleanup
Static function wb_ntlm_initiate renamed to ntlm_wb_init
Static function wb_ntlm_response renamed to ntlm_wb_response

Feature string literal NTLM_SSO renamed to NTLM_WB.
Preprocessor symbol USE_NTLM_SSO renamed to WINBIND_NTLM_AUTH_ENABLED.
curl's 'long' option 'ntlm-sso' renamed to 'ntlm-wb'.
Fix some comments to make clear that this is actually a NTLM delegation.

Functions renamed:

Curl_output_ntlm_sso -> Curl_output_ntlm_wb
sso_ntlm_close -> wb_ntlm_close
sso_ntlm_response -> wb_ntlm_response
sso_ntlm_initiate -> wb_ntlm_initiate

Preprocessor symbols renamed:

CURLAUTH_NTLM_SSO -> CURLAUTH_NTLM_WB
CURL_VERSION_NTLM_SSO -> CURL_VERSION_NTLM_WB

Output of Curl_ntlm_create_type1_message() and Curl_ntlm_create_type3_message()
functions is now already base64 encoded.

include the prototype header

Fixed the order of the preferred SMTP authentication method to:
AUTH CRAM-MD5, AUTH LOGIN then AUTH PLAIN.

AUTH PLAIN should be the last as it slightly more insecure than AUTH LOGIN
as the username and password are sent together - there is no handshaking
between the client and server like there is with AUTH LOGIN.

Previous interfaces for these libcurl internal functions did not allow to tell
apart a legitimate zero size result from an error condition. These functions
now return a CURLcode indicating function success or otherwise specific error.
Output size is returned using a pointer argument.

All usage of these two functions, and others closely related, has been adapted
to the new interfaces. Relative error and OOM handling adapted or added where
missing. Unit test 1302 also adapted.

* Added function comments:
    - Curl_ntlm_decode_type2_message
    - Curl_ntlm_create_type1_message
    - Curl_ntlm_create_type3_message

* Modification of ntlm processing state to NTLMSTATE_TYPE2 is now done
  only when Curl_ntlm_decode_type2_message() has fully succeeded.

As a bonus, this lets our MemoryTracking subsystem track zlib operations.
And also fixes a shortcut some zlib 1.2.x versions took using malloc()
instead of calloc(), which would trigger memory debuggers warnings on
memory being used without having been initialized.

Follow-up to commit 5eb2396c as that wasn't complete.

At times HEADERFUNCTION+HEADERDATA was set only to have only HEADERDATA
set in the subsequent loop which could cause a NULL to get sent as
userdata to 'header_callback' which wasn't made to handle that.

Now HEADERFUNCTION is explicitly set to NULL if it isn't set to the
callback.