fix : incorrect POLLOUT def on horizonOS/armv6k-nintendo-3ds

[kore-signet]

Description

Current definition for POLLOUT is incorrect - as described here, it should be 0x08.

Unfortunately, it seems like the current definition for POLLERR is overlapping as 0x08. According to the linked docs, POLLERR is actually not a supported operation on this target (neither is POLLHUP, which is also currently defined).

I'm not super clear on what the best procedure would be here - should POLLERR & POLLHUP be deleted as definitions?

Sources

• https://www.3dbrew.org/wiki/SOCU:poll

Checklist

• Relevant tests in libc-test/semver have been updated
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI
  (libc-test does not currently support horizonOS, as far as I can tell?)