Auto merge of rust-lang#810 - oherrala:pthread_cancel, r=alexcrichton

Introduce pthread_cancel() for terminating threads

pthread_cancel() is safer way to terminate thread than pthread_kill().

This function can be found from ISO/IEC 9945-1:1996 (“POSIX.1”) and first introduced into Single Unix Specification version 2 on 1997.

Author: bors

src/unix/bsd/mod.rs

@@ -491,6 +491,9 @@ extern {
                            oldset: *mut sigset_t) -> ::c_int;
     pub fn sem_open(name: *const ::c_char, oflag: ::c_int, ...) -> *mut sem_t;
     pub fn getgrnam(name: *const ::c_char) -> *mut ::group;
+    #[cfg_attr(all(target_os = "macos", target_arch = "x86"),
+               link_name = "pthread_cancel$UNIX2003")]
+    pub fn pthread_cancel(thread: ::pthread_t) -> ::c_int;
     pub fn pthread_kill(thread: ::pthread_t, sig: ::c_int) -> ::c_int;
     pub fn sem_unlink(name: *const ::c_char) -> ::c_int;
     pub fn daemon(nochdir: ::c_int, noclose: ::c_int) -> ::c_int;

src/unix/notbsd/linux/mod.rs

@@ -1411,6 +1411,7 @@ extern {
                            oldset: *mut sigset_t) -> ::c_int;
     pub fn sem_open(name: *const ::c_char, oflag: ::c_int, ...) -> *mut sem_t;
     pub fn getgrnam(name: *const ::c_char) -> *mut ::group;
+    pub fn pthread_cancel(thread: ::pthread_t) -> ::c_int;
     pub fn pthread_kill(thread: ::pthread_t, sig: ::c_int) -> ::c_int;
     pub fn sem_unlink(name: *const ::c_char) -> ::c_int;
     pub fn daemon(nochdir: ::c_int, noclose: ::c_int) -> ::c_int;