Manually exclude Android instead of compiler cfg

This change is due to an unfortunate interaction between the `s!` macro
and the Android abi. When the struct is defined, but excluded through a
`[cfg(not(target_os = "android"))]` the macro tries to define a
non-existent struct. This commit manually add the functions & struct to
each platform independently.

Author: cjschneider2

src/unix/bsd/mod.rs

@@ -120,6 +120,11 @@ s! {
     pub struct fsid_t {
         __fsid_val: [::int32_t; 2],
     }
+
+    pub struct if_nameindex {
+        pub if_index: ::c_uint,
+        pub if_name: *mut ::c_char,
+    }
 }
 
 pub const LC_ALL: ::c_int = 0;
@@ -358,6 +363,8 @@ extern {
     pub fn getprogname() -> *const ::c_char;
     pub fn setprogname(name: *const ::c_char);
     pub fn getloadavg(loadavg: *mut ::c_double, nelem: ::c_int) -> ::c_int;
+    pub fn if_nameindex() -> *mut if_nameindex;
+    pub fn if_freenameindex(ptr: *mut if_nameindex);
 }
 
 cfg_if! {

src/unix/mod.rs

@@ -114,12 +114,6 @@ s! {
         pub l_onoff: ::c_int,
         pub l_linger: ::c_int,
     }
-
-   #[cfg(not(target_os = "android"))]
-    pub struct if_nameindex {
-        pub if_index: ::c_uint,
-        pub if_name: *mut ::c_char,
-    }
 }
 
 pub const SIG_DFL: sighandler_t = 0 as sighandler_t;

src/unix/notbsd/linux/mod.rs

@@ -181,6 +181,12 @@ s! {
         #[cfg(target_pointer_width = "64")]
         bits: [u64; 16],
     }
+
+    pub struct if_nameindex {
+        pub if_index: ::c_uint,
+        pub if_name: *mut ::c_char,
+    }
+
 }
 
 pub const ABDAY_1: ::nl_item = 0x20000;
@@ -637,6 +643,8 @@ extern {
     // Not available now on Android
     pub fn mkfifoat(dirfd: ::c_int, pathname: *const ::c_char,
                     mode: ::mode_t) -> ::c_int;
+    pub fn if_nameindex() -> *mut if_nameindex;
+    pub fn if_freenameindex(ptr: *mut if_nameindex);
 }
 
 cfg_if! {

src/unix/solaris/mod.rs

@@ -318,6 +318,11 @@ s! {
         pub l_pid: ::pid_t,
         pub l_pad: [::c_long; 4]
     }
+
+    pub struct if_nameindex {
+        pub if_index: ::c_uint,
+        pub if_name: *mut ::c_char,
+    }
 }
 
 pub const LC_CTYPE: ::c_int = 0;
@@ -990,21 +995,23 @@ extern {
     pub fn linkat(olddirfd: ::c_int, oldpath: *const ::c_char,
                   newdirfd: ::c_int, newpath: *const ::c_char,
                   flags: ::c_int) -> ::c_int;
-   pub fn mkdirat(dirfd: ::c_int, pathname: *const ::c_char,
-                  mode: ::mode_t) -> ::c_int;
-   pub fn mknodat(dirfd: ::c_int, pathname: *const ::c_char,
-                 mode: ::mode_t, dev: dev_t) -> ::c_int;
-   pub fn readlinkat(dirfd: ::c_int, pathname: *const ::c_char,
-                     buf: *mut ::c_char, bufsiz: ::size_t) -> ::ssize_t;
-   pub fn renameat(olddirfd: ::c_int, oldpath: *const ::c_char,
-                   newdirfd: ::c_int, newpath: *const ::c_char)
-                   -> ::c_int;
-   pub fn symlinkat(target: *const ::c_char, newdirfd: ::c_int,
-                    linkpath: *const ::c_char) -> ::c_int;
-   pub fn unlinkat(dirfd: ::c_int, pathname: *const ::c_char,
-                   flags: ::c_int) -> ::c_int;
-   pub fn mkfifoat(dirfd: ::c_int, pathname: *const ::c_char,
+    pub fn mkdirat(dirfd: ::c_int, pathname: *const ::c_char,
                    mode: ::mode_t) -> ::c_int;
-   pub fn sethostname(name: *const ::c_char, len: ::size_t) -> ::c_int;
+    pub fn mknodat(dirfd: ::c_int, pathname: *const ::c_char,
+                   mode: ::mode_t, dev: dev_t) -> ::c_int;
+    pub fn readlinkat(dirfd: ::c_int, pathname: *const ::c_char,
+                      buf: *mut ::c_char, bufsiz: ::size_t) -> ::ssize_t;
+    pub fn renameat(olddirfd: ::c_int, oldpath: *const ::c_char,
+                    newdirfd: ::c_int, newpath: *const ::c_char)
+                    -> ::c_int;
+    pub fn symlinkat(target: *const ::c_char, newdirfd: ::c_int,
+                     linkpath: *const ::c_char) -> ::c_int;
+    pub fn unlinkat(dirfd: ::c_int, pathname: *const ::c_char,
+                    flags: ::c_int) -> ::c_int;
+    pub fn mkfifoat(dirfd: ::c_int, pathname: *const ::c_char,
+                    mode: ::mode_t) -> ::c_int;
+    pub fn sethostname(name: *const ::c_char, len: ::size_t) -> ::c_int;
+    pub fn if_nameindex() -> *mut if_nameindex;
+    pub fn if_freenameindex(ptr: *mut if_nameindex);
 }