aarch64-linux-gnu: avoid double exporting of user_fpsimd_struct

Author: chenx97

src/unix/linux_like/linux/gnu/b64/aarch64/align.rs

@@ -27,13 +27,6 @@ s! {
         __reserved: [[u64; 32]; 16],
     }
 
-    #[repr(align(16))]
-    pub struct user_fpsimd_struct {
-        pub vregs: [[u64; 2]; 32],
-        pub fpsr: ::c_uint,
-        pub fpcr: ::c_uint,
-    }
-
     #[repr(align(8))]
     pub struct clone_args {
         pub flags: ::c_ulonglong,

src/unix/linux_like/linux/gnu/b64/aarch64/fallback.rs

@@ -0,0 +1,8 @@
+s! {
+    #[repr(align(16))]
+    pub struct user_fpsimd_struct {
+        pub vregs: [[u64; 2]; 32],
+        pub fpsr: ::c_uint,
+        pub fpcr: ::c_uint,
+    }
+}

src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs

@@ -934,5 +934,8 @@ cfg_if! {
     if #[cfg(libc_int128)] {
         mod int128;
         pub use self::int128::*;
+    } else {
+        mod fallback;
+        pub use self::fallback::*;
     }
 }