Handle stack_t.ss_sp type change for DragonFlyBSD

stack_t.ss_sp is now c_void on DragonFlyBSD, so the specialization is no longer needed.

Changed in rust-lang/libc@02922ef.

library/std/src/sys/unix/stack_overflow.rs

@@ -161,24 +161,10 @@ mod imp {
         stackp.add(page_size())
     }
 
-    #[cfg(any(
-        target_os = "linux",
-        target_os = "macos",
-        target_os = "freebsd",
-        target_os = "netbsd",
-        target_os = "openbsd",
-        target_os = "solaris",
-        target_os = "illumos"
-    ))]
     unsafe fn get_stack() -> libc::stack_t {
         libc::stack_t { ss_sp: get_stackp(), ss_flags: 0, ss_size: SIGSTKSZ }
     }
 
-    #[cfg(target_os = "dragonfly")]
-    unsafe fn get_stack() -> libc::stack_t {
-        libc::stack_t { ss_sp: get_stackp() as *mut i8, ss_flags: 0, ss_size: SIGSTKSZ }
-    }
-
     pub unsafe fn make_handler() -> Handler {
         if !NEED_ALTSTACK.load(Ordering::Relaxed) {
             return Handler::null();