core: set default backend options before calling backend init

This commit restores the previous behavior with regards to setting some backend options and
restores the ability to set default context options before libusb_init. None of the backends
use anything set in init in their set_option function so this should be safe with all
backends and options.

References #942

Signed-off-by: Nathan Hjelm <hjelmn@google.com>
2 files changed