add support for Linux on AArch64, MIPS(64), PowerPC(64) and SPARC64 (#43)

by switching from the syscall crate to the sc crate. The sc crate is a
fork of the syscall crate that adds supports for several other
platforms.

shim/Cargo.toml

@@ -13,4 +13,4 @@ debug-assertions = false
 codegen-units = 1
 
 [dependencies]
-syscall = "0.2.1"
+sc = "0.1.0"

shim/src/lib.rs

@@ -12,7 +12,7 @@
 #![warn(missing_docs)]
 
 #[macro_use]
-extern crate syscall;
+extern crate sc;
 
 pub mod config;
 pub mod thread_destructor;