This patch adds a ptrace based gdb backend, which is then enlightended
to known how to read the serenity i386 registers via ptrace.
This is just a basic implementation to get the port bootstrapped.
Stack regions can't be made volatile, which makes it impossible for
malloc to manage memory that's used for `sigaltstack()`. Let's use mmap
instead.
Co-authored-by: Idan Horowitz <idan.horowitz@gmail.com>
