devel/llvm-devel: fix compiler-rt build on current

Bump cpuset size to 1024 on newer current. Newly added sanitizer
support for cpuset_getaffinity(2) hardcodes the size so bump it to
match CPU_MAXSIZE (it's not obviously possible to extract it from
sys/_cpuset.h).

PR: 272235
Issue: https://github.com/llvm/llvm-project/issues/63485
Submitted by: jfc@mit.edu