Auto merge of #2664 - rschulman:master, r=joshtriplett

Add 400-series syscalls to musl riscv64 definitions

This PR adds 19 missing syscalls to the riscv64 musl definitions. The missing calls were copied directly from the riscv64 GNU definitions. The missing definitions (in particular `SYS_clone3`) are preventing compiling `std` for `riscv64gc-unknown-linux-musl`.

src/unix/linux_like/linux/musl/b64/riscv64/mod.rs

@@ -465,6 +465,25 @@ pub const SYS_pkey_mprotect: ::c_long = 288;
 pub const SYS_pkey_alloc: ::c_long = 289;
 pub const SYS_pkey_free: ::c_long = 290;
 pub const SYS_statx: ::c_long = 291;
+pub const SYS_pidfd_send_signal: ::c_long = 424;
+pub const SYS_io_uring_setup: ::c_long = 425;
+pub const SYS_io_uring_enter: ::c_long = 426;
+pub const SYS_io_uring_register: ::c_long = 427;
+pub const SYS_open_tree: ::c_long = 428;
+pub const SYS_move_mount: ::c_long = 429;
+pub const SYS_fsopen: ::c_long = 430;
+pub const SYS_fsconfig: ::c_long = 431;
+pub const SYS_fsmount: ::c_long = 432;
+pub const SYS_fspick: ::c_long = 433;
+pub const SYS_pidfd_open: ::c_long = 434;
+pub const SYS_clone3: ::c_long = 435;
+pub const SYS_close_range: ::c_long = 436;
+pub const SYS_openat2: ::c_long = 437;
+pub const SYS_pidfd_getfd: ::c_long = 438;
+pub const SYS_faccessat2: ::c_long = 439;
+pub const SYS_process_madvise: ::c_long = 440;
+pub const SYS_epoll_pwait2: ::c_long = 441;
+pub const SYS_mount_setattr: ::c_long = 442;
 
 pub const O_APPEND: ::c_int = 1024;
 pub const O_DIRECT: ::c_int = 0x4000;