Most signal-related tests fail on AArch32 on certain platforms

[egrimley-arm]

It looks like almost every test with sig in the name fails in an AArch32 Debian 10 container under a 64-bit 5.15.0 Linux kernel running on Neoverse N1 (Graviton 2) or Neoverse V1 (Graviton 3). The same tests do not fail in an AArch32 Debian 10 container under a 64-bit 5.4.47 Linux kernel running on Cortex-A72. This is with DEBUG. In particular, the tests code_api|linux.signalXXXX and code_api|linux.sigplainXXX fail on the Gravitons but not on the other platform.

(The signal-related tests also fail with Debian 11 or Debian 12 on the Gravitons, and there are additional failures with Debian 11 or Debian 12.)

Unfortunately I don't have the ability to try different kernel versions on the shared machines I have access to, so further data points would be helpful. (Is it the kernel or the hardware that makes the difference?)