Remove __SIGRTMIN and __SIGRTMAX from musl include wrappers am: ec716ff7c6 am: 6788d97952 am: e720656d1f

Original change: https://android-review.googlesource.com/c/platform/external/musl/+/2262411

Change-Id: I376126c6fb7122aecbcdb065976d0c7f398f05d0
Signed-off-by: Automerger Merge Worker <[email protected]>