Add SGX target

Author: Jethro Beekman

src/lib.rs

@@ -199,6 +199,9 @@ cfg_if! {
     } else if #[cfg(unix)] {
         mod unix;
         pub use unix::*;
+    } else if #[cfg(target_env = "sgx")] {
+        mod sgx;
+        pub use sgx::*;
     } else {
         // Unknown target_family
     }

src/sgx.rs

@@ -0,0 +1,3 @@
+pub type c_char = i8;
+pub type c_long = i64;
+pub type c_ulong = u64;