add cyassl options, update to LWS_ cmake syntax
win32 provide empty declaration for inline

Signed-off-by: Andy Green <andy.green@linaro.org>
Define libwebsocket_write_http as a macro instead of inline

This solves two problems:
a) We do not need to use the keyword inline in the public header.
b) We avoid a possible warning about an unused static function.
Fix installation into relative installation directory

This is required to make the other CPack generators like "ZIP" work.