Reading /proc/self/task/<pid>/maps is not remapped to the target

This bug has been copied automatically from: https://bugs.launchpad.net/qemu/+bug/1808565
Reported by 'Alan Jones' on 2018-12-14 :

Seeing this in qemu-user 3.1.0

The code in is_proc_myself which supports remapping of /proc/self/maps and
/proc/<pid>/maps does not support remapping of /proc/self/task/<pid>/maps
or /proc/<pid>/task/<pid>/maps. Extending is_proc_myself to cover these
cases causes the maps to be rewritten correctly.

These are useful in multithreaded programs to avoid freezing the entire
program to capture the maps for a single tid.