posix: cpp: Fix test application build

[finikorg]

First patch enables test also for posix and second fixes the bug

[codecov-io]

Codecov Report

Merging #9533 into master will decrease coverage by 0.1%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #9533      +/-   ##
==========================================
- Coverage   52.27%   52.17%   -0.11%     
==========================================
  Files         307      215      -92     
  Lines       45469    26013   -19456     
  Branches    10526     5594    -4932     
==========================================
- Hits        23770    13572   -10198     
+ Misses      16901    10183    -6718     
+ Partials     4798     2258    -2540

Impacted Files	Coverage Δ
include/bluetooth/buf.h	0% <0%> (-100%)	⬇️
include/drivers/bluetooth/hci_driver.h	0% <0%> (-100%)	⬇️
subsys/random/rand32_timer.c	0% <0%> (-100%)	⬇️
include/bluetooth/hci.h	0% <0%> (-77.78%)	⬇️
drivers/console/native_posix_console.c	22.36% <0%> (-50.36%)	⬇️
subsys/logging/log_output.c	2.72% <0%> (-44.87%)	⬇️
subsys/usb/usb_descriptor.c	0% <0%> (-44.59%)	⬇️
subsys/bluetooth/host/hci_core.c	2.56% <0%> (-41.52%)	⬇️
include/misc/byteorder.h	56.81% <0%> (-40.91%)	⬇️
lib/cmsis_rtos_v1/cmsis_msgq.c	35.89% <0%> (-39.72%)	⬇️
... and 330 more

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[finikorg]

@nashif apparently docker is missing g++-multilib

[nashif]

@nashif apparently docker is missing g++-multilib

it is installed, maybe something else is missing, can you find out which lib is that?