Fix build on arm and s390x after recent libc changes

libc just removed some symbols on linux/arm32 and linux/s390x that never
should've been defined in the first place.

rust-lang/libc@24f8972
rust-lang/libc@d269543

Author: asomers

src/sys/ptrace/linux.rs

@@ -45,31 +45,27 @@ libc_enum!{
                   all(target_os = "linux", any(target_env = "musl",
                                                target_arch = "mips",
                                                target_arch = "mips64",
-                                               target_arch = "s390x",
                                                target_arch = "x86_64",
                                                target_pointer_width = "32"))))]
         PTRACE_GETREGS,
         #[cfg(any(all(target_os = "android", target_pointer_width = "32"),
                   all(target_os = "linux", any(target_env = "musl",
                                                target_arch = "mips",
                                                target_arch = "mips64",
-                                               target_arch = "s390x",
                                                target_arch = "x86_64",
                                                target_pointer_width = "32"))))]
         PTRACE_SETREGS,
         #[cfg(any(all(target_os = "android", target_pointer_width = "32"),
                   all(target_os = "linux", any(target_env = "musl",
                                                target_arch = "mips",
                                                target_arch = "mips64",
-                                               target_arch = "s390x",
                                                target_arch = "x86_64",
                                                target_pointer_width = "32"))))]
         PTRACE_GETFPREGS,
         #[cfg(any(all(target_os = "android", target_pointer_width = "32"),
                   all(target_os = "linux", any(target_env = "musl",
                                                target_arch = "mips",
                                                target_arch = "mips64",
-                                               target_arch = "s390x",
                                                target_arch = "x86_64",
                                                target_pointer_width = "32"))))]
         PTRACE_SETFPREGS,
@@ -78,14 +74,12 @@ libc_enum!{
         #[cfg(all(target_os = "linux", any(target_env = "musl",
                                            target_arch = "mips",
                                            target_arch = "mips64",
-                                           target_arch = "arm",
                                            target_arch = "x86",
                                            target_arch = "x86_64")))]
         PTRACE_GETFPXREGS,
         #[cfg(all(target_os = "linux", any(target_env = "musl",
                                            target_arch = "mips",
                                            target_arch = "mips64",
-                                           target_arch = "arm",
                                            target_arch = "x86",
                                            target_arch = "x86_64")))]
         PTRACE_SETFPXREGS,