Update private-libwebsockets.h

fixes windows http file serve - macro compatible_file_read() incorrectly used 'amount' instead of '_amount'
define LWS_SSL_CAPPABLE return codes even when no SSL enabled

Reported by fuzzy
https://github.com/warmcat/libwebsockets/issues/107

Signed-off-by: Andy Green <andy.green@linaro.org>
move SNI temp var back one

Reported as making trouble on Windows by spayton

https://github.com/warmcat/libwebsockets/issues/109

Signed-off-by: Andy Green <andy.green@linaro.org>