cmake: fix enabling LDAPS on Windows

cmake: fix enabling LDAPS on Windows

Before this patch, enabling LDAPS required a manual C flag:
https://github.com/curl/curl-for-win/blob/c1cfc31cfc04f24f7a4f946564d6f0e1b4d7dd36/curl-cmake.sh#L105

Fix this and enable LDAPS automatically when using `wldap32` (and
when not explicitly disabled). This matches autotools and `Makefile.mk`
behavior. Also remove issue from KNOWN_BUGS.

Add workaround for MSVS 2010 warning triggered by LDAPS now enabled
in more CI tests:
`ldap.c(360): warning C4306: 'type cast' : conversion from 'int' to 'void *' of greater size`
Ref: https://ci.appveyor.com/project/curlorg/curl/builds/46408284/job/v8mwl9yfbmoeqwlr#L312

Reported-by: JackBoosY on github
Reviewed-by: Jay Satiro
Reviewed-by: Marcel Raad
Fixes #6284
Closes #10674