arc4random api for haiku

(backport <#3945>)
(cherry picked from commit 8924123)

Author: devnexen

libc-test/build.rs

@@ -4834,6 +4834,7 @@ fn test_haiku(target: &str) {
                "libutil.h",
                "link.h",
                "pty.h",
+               "stdlib.h",
                "stringlist.h",
                "sys/link_elf.h",
     }

src/unix/haiku/mod.rs

@@ -2133,6 +2133,10 @@ extern "C" {
         >,
         data: *mut ::c_void,
     ) -> ::c_int;
+
+    pub fn arc4random() -> u32;
+    pub fn arc4random_uniform(upper_bound: u32) -> u32;
+    pub fn arc4random_buf(buf: *mut ::c_void, n: ::size_t);
 }
 
 #[link(name = "gnu")]