Refactor linux x86_64 module

src/unix/linux_like/linux/gnu/b64/mod.rs

@@ -77,15 +77,6 @@ cfg_if! {
     } else if #[cfg(any(target_arch = "x86_64"))] {
         mod x86_64;
         pub use self::x86_64::*;
-        cfg_if! {
-            if #[cfg(target_pointer_width = "32")] {
-                mod x32;
-                pub use self::x32::*;
-            } else {
-                mod not_x32;
-                pub use self::not_x32::*;
-            }
-        }
     } else {
         // Unknown target_arch
     }

src/unix/linux_like/linux/gnu/b64/x86_64/mod.rs

@@ -866,3 +866,14 @@ extern {
     pub fn ioperm(from: ::c_ulong, num: ::c_ulong,
                   turn_on: ::c_int) -> ::c_int;
 }
+
+
+cfg_if! {
+    if #[cfg(target_pointer_width = "32")] {
+        mod x32;
+        pub use self::x32::*;
+    } else {
+        mod not_x32;
+        pub use self::not_x32::*;
+    }
+}