[llvm-branch-commits] [libc] Drop elf.h include from dl_phdr_info header (PR #193653)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/193653

This is a public header which can cause problems in some build
configurations (e.g., clang fails to find elf.h in my build
configuration given it is hermetic). All the types that are actually
needed in the file are also included properly through the internal
headers through link-macros.h.