Support TUNSETIFF on MIPS, PPC and SPARC

This commit adds support for the TUNSETIFF constant on MIPS, PPC and
SPARC. The TUNSETIFF constant defined in the Linux kernel headers uses
architecture-specific macros. For this commit, the architecture-specific
definitions of the constant in the Golang source code were consulted.

src/phy/sys/linux.rs

@@ -5,7 +5,22 @@ pub const SIOCGIFINDEX: libc::c_ulong = 0x8933;
 pub const ETH_P_ALL: libc::c_short = 0x0003;
 pub const ETH_P_IEEE802154: libc::c_short = 0x00F6;
 
-pub const TUNSETIFF: libc::c_ulong = 0x400454CA;
+// Constant definition as per
+// https://github.com/golang/sys/blob/master/unix/zerrors_linux_<arch>.go
+pub const TUNSETIFF: libc::c_ulong = if cfg!(any(
+    target_arch = "mips",
+    target_arch = "mips64",
+    target_arch = "mips64el",
+    target_arch = "mipsel",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "powerpc64le",
+    target_arch = "sparc64"
+)) {
+    0x800454CA
+} else {
+    0x400454CA
+};
 pub const IFF_TUN: libc::c_int = 0x0001;
 pub const IFF_TAP: libc::c_int = 0x0002;
 pub const IFF_NO_PI: libc::c_int = 0x1000;