On ppc64 and ppc64le systems, glibc 2.23-or-less has a bug in malloc, that it only guarantees alignment to 8 bytes, even though it should be 16 bytes.

https://sourceware.org/bugzilla/show_bug.cgi?id=6527

This is a problem for the long-double (float128) and sometimes complex128 type which should be aligned to 16 bytes. This means that when using long-double arrays, many internal numpy computations will randomly fail on ppc64, depending on what alignment malloc returned. This causes sporadic numpy unit test failures and sometimes outright crashes. The test numpy.core.tests.test_numeric TestRequire.test_require_each commonly fails, though not consistently.

Users on ppc64 should upgrade to glibc 2.24 or later.

(Discovered in #10443)