Stop the abuse of CURLE_FAILED_INIT as return code for things not being
init related by introducing two new return codes:
CURLE_NOT_BUILT_IN and CURLE_UNKNOWN_OPTION
CURLE_NOT_BUILT_IN replaces return code 4 that has been obsoleted for
several years. It is used for returning error when something is
attempted to be used but the feature/option was not enabled or
explictitly disabled at build-time. Getting this error mostly means that
libcurl needs to be rebuilt.
CURLE_FAILED_INIT is now saved and used strictly for init
failures. Getting this problem means something went seriously wrong,
like a resource shortage or similar.
CURLE_UNKNOWN_OPTION is the option formerly known as
CURLE_UNKNOWN_TELNET_OPTION (and the old name is still present,
separately defined to be removed in a very distant future). This error
code is meant to be used to return when an option is given to libcurl
that isn't known. This problem would mostly indicate a problem in the
program that uses libcurl.
Failed HTTPS tests: 301, 306, 311, 312, 313, 560
311, 312 need more detailed error reporting from axTLS.
313 relates to CRL, which hasn't been implemented yet.
Added axTLS to autotool files and glue code to misc other files.
axtls.h maps SSL API functions, but may change.
axtls.c is just a stub file and will definitely change.
