NetBSD: add basic types for aarch64

src/unix/bsd/netbsdlike/netbsd/aarch64.rs

+pub type c_long = i64;
+pub type c_ulong = u64;
+pub type c_char = u8;

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

@@ -1110,7 +1110,10 @@ extern {
 }
 
 cfg_if! {
-    if #[cfg(target_arch = "arm")] {
+    if #[cfg(target_arch = "aarch64")] {
+        mod aarch64;
+        pub use self::aarch64::*;
+    } else if #[cfg(target_arch = "arm")] {
         mod arm;
         pub use self::arm::*;
     } else if #[cfg(target_arch = "powerpc")] {