Merge a8d7511811c7d7c689c3e8f858e8e00a56aba152 into 18.x

[brad0]

[llvm-readobj] Add support for the PT_OPENBSD_SYSCALLS
segment type. (#82122)

Reference: https://github.com/openbsd/src/blob/master/sys/sys/exec_elf.h

[brad0]

/cherry-pick a8d7511

[llvmbot]

/pull-request #82318