Review the patch on Android's ProxySelector

We have an old commit (a16d36fc) to patch org.mozilla.gecko.util.ProxySelector to use Tor as a proxy.

I see several problems with it:

• The address is hardcoded to the former default, which is wrong after we switched the backend
• Currently, it seems to me openConnectionWithProxy is used only by the crash reporter. The crash reporter is on its own for $reasons (at least being able to send a crash report even though the rest of the app crashed), so tor might not be working anymore when it's invoked. We disable the crash reporter in the mozconfig, but we might also make sendCrashReport a nop, for security in depth.
• The ProxySelector does more stuff. I think it's a bridge for proxy auto configuration. If I remember correctly, we don't disable these mechanisms on other platforms, but I wouldn't mind someone to check I didn't get this wrong.