ptrace: Fix request type for non-GNU s390x

[Gelbpunkt]

What does this PR do

The type of the ptrace request parameter is architecture-independent in libc and only c_uint for uclibc and glibc on Linux. This fixes compilation against non-glibc s390x targets like s390x-unknown-linux-musl.

Ref:

~/libc $ rg "ptrace\(request"
src/unix/bsd/netbsdlike/openbsd/mod.rs
2009:    pub fn ptrace(request: c_int, pid: crate::pid_t, addr: caddr_t, data: c_int) -> c_int;

src/unix/bsd/freebsdlike/mod.rs
1682:    pub fn ptrace(request: c_int, pid: crate::pid_t, addr: *mut c_char, data: c_int) -> c_int;

src/unix/bsd/netbsdlike/netbsd/mod.rs
2584:    pub fn ptrace(request: c_int, pid: crate::pid_t, addr: *mut c_void, data: c_int) -> c_int;

src/unix/bsd/apple/mod.rs
5428:    pub fn ptrace(request: c_int, pid: crate::pid_t, addr: *mut c_char, data: c_int) -> c_int;

src/unix/linux_like/android/mod.rs
3633:    pub fn ptrace(request: c_int, ...) -> c_long;

src/unix/linux_like/linux/uclibc/mod.rs
443:    pub fn ptrace(request: c_uint, ...) -> c_long;

src/unix/linux_like/linux/musl/mod.rs
872:    pub fn ptrace(request: c_int, ...) -> c_long;

src/unix/linux_like/linux/gnu/mod.rs
1201:    pub fn ptrace(request: c_uint, ...) -> c_long;

Checklist:

• I have read CONTRIBUTING.md
• I have written necessary tests and rustdoc comments
• A change log has been added if this PR modifies nix's API