Remove all the unused mutex/rwlock/condvars from sys

Author: faern

src/libstd/sys/cloudabi/condvar.rs

@@ -19,14 +19,11 @@ pub mod args;
 pub mod backtrace;
 #[path = "../unix/cmath.rs"]
 pub mod cmath;
-pub mod condvar;
 #[path = "../unix/memchr.rs"]
 pub mod memchr;
-pub mod mutex;
 pub mod os;
 #[path = "../unix/os_str.rs"]
 pub mod os_str;
-pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;