Fix RISC-V support

Don't try to use PTRACE_[GS]ETREGS, PTRACE_[GS]ETFPREGS or
PTRACE_[GS]ETFPXREGS on riscv64, they are legacy-only.

Author: andreas-schwab

src/sys/ptrace/linux.rs

@@ -48,31 +48,27 @@ libc_enum!{
                                                target_arch = "mips",
                                                target_arch = "mips64",
                                                target_arch = "x86_64",
-                                               target_arch = "riscv64",
                                                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 = "x86_64",
-                                               target_arch = "riscv64",
                                                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 = "x86_64",
-                                               target_arch = "riscv64",
                                                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 = "x86_64",
-                                               target_arch = "riscv64",
                                                target_pointer_width = "32"))))]
         PTRACE_SETFPREGS,
         PTRACE_ATTACH,
@@ -81,15 +77,13 @@ libc_enum!{
                                            target_arch = "mips",
                                            target_arch = "mips64",
                                            target_arch = "x86",
-                                           target_arch = "x86_64",
-                                           target_arch = "riscv64")))]
+                                           target_arch = "x86_64")))]
         PTRACE_GETFPXREGS,
         #[cfg(all(target_os = "linux", any(target_env = "musl",
                                            target_arch = "mips",
                                            target_arch = "mips64",
                                            target_arch = "x86",
-                                           target_arch = "x86_64",
-                                           target_arch = "riscv64")))]
+                                           target_arch = "x86_64")))]
         PTRACE_SETFPXREGS,
         PTRACE_SYSCALL,
         PTRACE_SETOPTIONS,