[AnHero] Delete CrashDialog on close for #1490.
[AnHero] Style fix.
[AnHero] Wait only for crash handler process.

Previously we've waited for all child processed, and there can be quite a
few of them.

For #1490.
[AnHero] Keep and destroy the GDBLauncher for #1490.
[AnHero] Wait/kill gdb process in GDBLauncher dtor.

This finally fixes #1490.