The tests posix/bug-ga2-mem and resolv/mtrace-tst-leaks2 are failing on
fedora 33 as mtrace reports memory leaks.
The /etc/nsswitch.conf differs between
Fedora 32: hosts: files dns myhostname
Fedora 33: hosts: files resolve [!UNAVAIL=return] myhostname dns
Therefore /lib64/libnss_resolve.so.2 (from systemd) and the dependencies
libgcc_s.so.1 and libpthread.so.0 are loaded.
Usually all malloc'ed resources from getaddrinfo / gethostbyname are freed
and the libraries are dlclose'd in nss/nsswitch.c:libc_freeres_fn (free_mem).
Unfortunately, /lib64/libnss_resolve.so.2 is marked with DF_1_NODELETE.
As this library is not unmapped, you'll see "Memory not freed".
Therefore those tests are now only relying on libnss_files.so by making
them test-container tests and providing the required configuration files.
By moving the tests to tests-container, those are now running with
"make check". Therefore the mtrace part of the tests are also moved
from "make xcheck" to "make check".
bug-ga2.c is now using test-driver.c in order to support WAIT_FOR_DEBUGGER
environment variable.
