std.http.Client: default to lazy root cert scanning
After this change, the system will be inspected for root certificates
only upon the first https request that actually occurs. This makes the
compiler no longer do SSL certificate scanning when running `zig build`
if no network requests are made.
d56a65a8c4Andrew Kelley committed on 1/17/2023, 6:44:56 AMparente646bec