Auto merge of rust-lang#527 - philippkeller:master, r=alexcrichton

add tmpnam and pthread_exit

tmpnam and readdir are trivial IMO.

About the `pthread_create` change: It needs `unsafe` for passing `C` functions to pthread_create (with rust functions the omission of `unsafe` is working of course).

`bindgen` produces this function definition:

```
pub fn pthread_create(arg1: *mut pthread_t,
                      arg2: *const pthread_attr_t,
                      arg3: Option<unsafe extern "C" fn(arg1: *mut c_void) -> *mut c_void>,
                      arg4: *mut c_void) -> c_int;
```

So it would add an additional `Option` around the function. But that would break existing code which uses `libc::pthread_create` and what use is it to call pthread_create without any function pointer, so I left `Option` out.

For reference: I also opened a [stackoverflow question](http://stackoverflow.com/questions/42284562) where the answers were also suggesting adding `unsafe` to the function definition.

src/unix/mod.rs

@@ -549,6 +549,7 @@ extern {
                link_name = "pthread_join$UNIX2003")]
     pub fn pthread_join(native: ::pthread_t,
                         value: *mut *mut ::c_void) -> ::c_int;
+    pub fn pthread_exit(value: *mut ::c_void);
     pub fn pthread_attr_init(attr: *mut ::pthread_attr_t) -> ::c_int;
     pub fn pthread_attr_destroy(attr: *mut ::pthread_attr_t) -> ::c_int;
     pub fn pthread_attr_setstacksize(attr: *mut ::pthread_attr_t,
@@ -846,6 +847,7 @@ extern {
     pub fn mkstemp(template: *mut ::c_char) -> ::c_int;
     pub fn mkstemps(template: *mut ::c_char, suffixlen: ::c_int) -> ::c_int;
     pub fn mkdtemp(template: *mut ::c_char) -> *mut ::c_char;
+    pub fn tmpnam(ptr: *mut ::c_char) -> *mut ::c_char;
     pub fn futimes(fd: ::c_int, times: *const ::timeval) -> ::c_int;
     pub fn nl_langinfo(item: ::nl_item) -> *mut ::c_char;