Replace all http://libusb.info/ with https

The libusb.info website, like most sites these days, auto-redirects to
the https version anyway.

Also replaced a couple of other http links to https, after verifying
that they autoredirect to https.

Note this changes the "describe" field in the version info returned by
libusb_get_version(). This field is only there for ABI compatibility and
contains the website URL.

Closes #1407
14 files changed