add timeout to gdbserver

[Ordoviz]

Bug 26116 in gdbserver causes pwn.gdb.debug() to hang on certain systems. Several users are affected by this, see #2030, #2060, and here. Since it doesn't look like the bug is getting fixed soon, we should try to detect it and offer a workaround. Many users had success with env={}. This will cause gdbserver to use /bin/sh instead of $SHELL.

I'm experiencing this bug with SHELL=/bin/fish. Setting SHELL=/bin/bash or using env={} fixes it.

[peace-maker]

Can you add the info about the SHELL environment variable being the problem to that message instead of suggesting to remove all envvars. That might help when the exploit actually needs some environment variables to be set.

[peace-maker]

Thank you!