NetBSD/mipsel: add support.

This follows rust-lang/rust#117356.

src/unix/bsd/netbsdlike/netbsd/mips.rs

@@ -0,0 +1,21 @@
+use PT_FIRSTMACH;
+
+pub type c_long = i32;
+pub type c_ulong = u32;
+pub type c_char = i8;
+pub type __cpu_simple_lock_nv_t = ::c_int;
+
+cfg_if! {
+    if #[cfg(libc_const_size_of)] {
+         #[doc(hidden)]
+         pub const _ALIGNBYTES: usize = ::mem::size_of::<::c_longlong>() - 1;
+    } else {
+         #[doc(hidden)]
+         pub const _ALIGNBYTES: usize = 8 - 1;
+    }
+}
+
+pub const PT_GETREGS: ::c_int = PT_FIRSTMACH + 1;
+pub const PT_SETREGS: ::c_int = PT_FIRSTMACH + 2;
+pub const PT_GETFPREGS: ::c_int = PT_FIRSTMACH + 3;
+pub const PT_SETFPREGS: ::c_int = PT_FIRSTMACH + 4;

src/unix/bsd/netbsdlike/netbsd/mod.rs

@@ -3203,6 +3203,9 @@ cfg_if! {
     } else if #[cfg(target_arch = "x86")] {
         mod x86;
         pub use self::x86::*;
+    } else if #[cfg(target_arch = "mips")] {
+        mod mips;
+        pub use self::mips::*;
     } else if #[cfg(target_arch = "riscv64")] {
         mod riscv64;
         pub use self::riscv64::*;