Rollup merge of rust-lang#25140 - kevinmehall:mips, r=steveklabnik

Building with `--target=mipsel-unknown-linux-gnu` currently results in the following errors, fixed by this PR:

```
rustc: x86_64-unknown-linux-gnu/stage2/lib/rustlib/mipsel-unknown-linux-gnu/lib/libstd
/vol/rust/src/libstd/os/linux/raw.rs:76:21: 76:28 error: use of undeclared type name `c_ulong`
/vol/rust/src/libstd/os/linux/raw.rs:76         pub st_dev: c_ulong,
                                                            ^~~~~~~
/vol/rust/src/libstd/os/linux/raw.rs:83:22: 83:29 error: use of undeclared type name `c_ulong`
/vol/rust/src/libstd/os/linux/raw.rs:83         pub st_rdev: c_ulong,
                                                             ^~~~~~~
/vol/rust/src/libstd/sys/common/net2.rs:210:52: 210:70 error: unresolved name `libc::TCP_KEEPIDLE`
/vol/rust/src/libstd/sys/common/net2.rs:210         setsockopt(&self.inner, libc::IPPROTO_TCP, libc::TCP_KEEPIDLE,
```

Author: Manishearth

src/liblibc/lib.rs

@@ -3624,6 +3624,30 @@ pub mod consts {
             pub const IPV6_DROP_MEMBERSHIP: c_int = 21;
 
             pub const TCP_NODELAY: c_int = 1;
+            pub const TCP_MAXSEG: c_int = 2;
+            pub const TCP_CORK: c_int = 3;
+            pub const TCP_KEEPIDLE: c_int = 4;
+            pub const TCP_KEEPINTVL: c_int = 5;
+            pub const TCP_KEEPCNT: c_int = 6;
+            pub const TCP_SYNCNT: c_int = 7;
+            pub const TCP_LINGER2: c_int = 8;
+            pub const TCP_DEFER_ACCEPT: c_int = 9;
+            pub const TCP_WINDOW_CLAMP: c_int = 10;
+            pub const TCP_INFO: c_int = 11;
+            pub const TCP_QUICKACK: c_int = 12;
+            pub const TCP_CONGESTION: c_int = 13;
+            pub const TCP_MD5SIG: c_int = 14;
+            pub const TCP_COOKIE_TRANSACTIONS: c_int = 15;
+            pub const TCP_THIN_LINEAR_TIMEOUTS: c_int = 16;
+            pub const TCP_THIN_DUPACK: c_int = 17;
+            pub const TCP_USER_TIMEOUT: c_int = 18;
+            pub const TCP_REPAIR: c_int = 19;
+            pub const TCP_REPAIR_QUEUE: c_int = 20;
+            pub const TCP_QUEUE_SEQ: c_int = 21;
+            pub const TCP_REPAIR_OPTIONS: c_int = 22;
+            pub const TCP_FASTOPEN: c_int = 23;
+            pub const TCP_TIMESTAMP: c_int = 24;
+
             pub const SOL_SOCKET: c_int = 65535;
 
             pub const SO_DEBUG: c_int = 0x0001;

src/libstd/os/linux/raw.rs

@@ -60,8 +60,8 @@ mod arch {
 #[cfg(any(target_arch = "mips",
           target_arch = "mipsel"))]
 mod arch {
-    use super::{dev_t, mode_t};
-    use os::raw::c_long;
+    use super::mode_t;
+    use os::raw::{c_long, c_ulong};
     use os::unix::raw::{gid_t, uid_t};
 
     pub type blkcnt_t = i32;