* feature: Add `killthreads` command (closes#1580)
This command allows the user to quickly kill multiple threads by
specyfying their ids as arguments to this command. It also supports
the `--all` flag, which will kill overy thread except the currently
selected one. This is useful for use with the `checkpoint` command.
The killing is done by calling `pthread_exit(0)`.
* fix: try fixing building test binaries by enabling -lpthread
* fix: remove error message check when calling pthread_exit
Removed the message check, because the error messages difffer between
versions of GDB.
* fix: Improve UX of the killthreads command
Add an extended description of the command, some validation on the thread IDs
and suppress GDB output.
* fix: lint
* fix: put the multiline help text in the correct place
* tests: fix test failing due to a race condition when running in parrallel to other tests
Replaced asserts with loops which wait for a cundition to be met, so that the tests doesn't fail due to scheduling issues.
* tests: add more fixes for race conditions in test_killthreads
* fix: lint
* Update pwndbg/commands/killthreads.py
* tests: Wait for exactly three threads
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Co-authored-by: Disconnect3d <dominik.b.czarnota@gmail.com>