ASSERT in sigaction_nosignals test

The sigaction_nosignals test asserts natively:

$ suite/tests/bin/linux.sigaction_nosignals
linux.sigaction_nosignals: src/suite/tests/linux/sigaction_nosignals.c:201: test_rw: Assertion `memcmp(test_rw_sys, test_rw_sim, sizeof(test_rw_sys)) == 0' failed.
Aborted

It passes under DR on most systems, but on a custom Linux distro it fails with the same assert.