Don't crash route selection when the system proxy selector throws

[SAY-5]

Fixes #9469.

When no explicit proxy is configured, RouteSelector calls address.proxySelector.select(uri) and only handles a null/empty return. On Android the platform DefaultProxySelector can itself throw IllegalArgumentException: port out of range:-1 when a system proxy is configured (via APN/MDM) with an unset port. That exception propagates out of resetNextProxy and crashes the call on the dispatcher thread, even though OkHttp already rejects out-of-range proxy ports elsewhere.

This treats a throwing ProxySelector.select() the same as a null/empty result and falls back to a direct connection, which matches how the surrounding code already handles "no usable proxy". Added a RouteSelectorTest case that fails on the current code and passes with the fix.

[swankjesse]

Great test.