How to elf/tst-ldconfig-* in cross test setup

[DJ Delorie]

Vineet Gupta <Vineet.Gupta1@synopsys.com> writes:
> When you say containers is this linux cgroups or something at a higher
> level: does it need any specific distro container package. Please
> remember this is a constrained system built off of buildroot.

It should not require anything beyond what kernel/glibc provides - we
even build our own /bin/sh for in-container use.  All the
containerization code is in support/test-container.c.  However, some
kernels and/or OSs are *configured* (i.e. for security reasons) to
disallow certain types of namespace unsharing - those should be detected
by test-container and flagged as unsupported tests.

By "container" I mean a simple filesystem/pid namespace using unshare,
sort of a fancy chroot() but it changes your UID and PID also.

See https://developers.redhat.com/blog/2018/11/16/microcontainers-for-unit-testing/
for some background info.