Android: correct statfs64.f_fsid type & visibility

The visibility has been not public since the initial commit[1]. But there
is no reason to hide this struct member specifically.

The type has also been "__fsid_t" in Android's bionic[2], so fix that as
well. This makes it consistent with statfs.f_fsid nicely.

[1] a36da11
[2] https://cs.android.com/search?q=file:bionic%2Flibc%20f_fsid

Author: victorhsieh

src/unix/linux_like/android/b32/mod.rs

@@ -74,7 +74,7 @@ s! {
         pub f_bavail: u64,
         pub f_files: u64,
         pub f_ffree: u64,
-        f_fsid: [u32; 2],
+        pub f_fsid: ::__fsid_t,
         pub f_namelen: u32,
         pub f_frsize: u32,
         pub f_flags: u32,

src/unix/linux_like/android/b64/mod.rs

@@ -84,7 +84,7 @@ s! {
         pub f_bavail: u64,
         pub f_files: u64,
         pub f_ffree: u64,
-        f_fsid: [u32; 2],
+        pub f_fsid: ::__fsid_t,
         pub f_namelen: u64,
         pub f_frsize: u64,
         pub f_flags: u64,