Stub for ptrace

It's happening...

src/platform/linux/mod.rs

@@ -15,6 +15,7 @@ use header::sys_utsname::utsname;
 use header::time::timespec;
 
 mod epoll;
+mod ptrace;
 mod signal;
 mod socket;
 

src/platform/linux/ptrace.rs

@@ -0,0 +1,9 @@
+use super::super::types::*;
+use super::super::PalPtrace;
+use super::{e, Sys};
+
+impl PalPtrace for Sys {
+    fn ptrace(request: c_int, pid: pid_t, addr: *mut c_void, data: *mut c_void) -> c_int {
+        unsafe { e(syscall!(PTRACE, request, pid, addr, data)) as c_int }
+    }
+}