valgrind: disable ptests

valgrind: disable ptests

The valgrind test runner, vg_regtest, changed in the 3.24 update and
there are some additional valgrind ptest regressions happening with glibc-2.41.
Disable the ptests for now. Some of the remaining patches can likely
be dropped but I'd rather carry them so that re-enabling the ptests
is simpler. Also the patch series have some dependencies and unwinding
that would block the glibc-2.41 unnecessarily.

This builds for glibc, musl for qemux86-64, runs:
-> valgrind [--leak-check=full] /bin/ls /tmp

Signed-off-by: Randy MacLeod <Randy.MacLeod@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>