Rollup merge of #53377 - cuviper:pointer-elf_size, r=alexcrichton

std: Use target_pointer_width for BACKTRACE_ELF_SIZE

The former code used `target.contains("64")` to detect Elf64 targets,
but this is inaccurate in a few cases:

- `s390x-unknown-linux-gnu` is 64-bit
- `sparcv9-sun-solaris` is 64-bit
- `x86_64-unknown-linux-gnux32` is 32-bit

Instead the `std` build script can use `CARGO_CFG_TARGET_POINTER_WIDTH`
to reliably detect 64-bit targets for libbacktrace.

Also update to backtrace-sys 0.1.24 for alexcrichton/backtrace-rs#122.

diff --cc src/Cargo.lock
Simple merge