FreeBSD: new rand()/srand() ABI in 13

https://reviews.freebsd.org/rS357382

src/unix/bsd/freebsdlike/freebsd/mod.rs

@@ -322,7 +322,14 @@ pub const EXTATTR_NAMESPACE_EMPTY: ::c_int = 0;
 pub const EXTATTR_NAMESPACE_USER: ::c_int = 1;
 pub const EXTATTR_NAMESPACE_SYSTEM: ::c_int = 2;
 
-pub const RAND_MAX: ::c_int = 0x7fff_fffd;
+cfg_if! {
+    if #[cfg(any(freebsd10, freebsd11, freebsd12))] {
+        pub const RAND_MAX: ::c_int = 0x7fff_fffd;
+    } else {
+        pub const RAND_MAX: ::c_int = 0x7fff_ffff;
+    }
+}
+
 pub const PTHREAD_STACK_MIN: ::size_t = MINSIGSTKSZ;
 pub const PTHREAD_MUTEX_ADAPTIVE_NP: ::c_int = 4;
 pub const SIGSTKSZ: ::size_t = MINSIGSTKSZ + 32768;

src/unix/bsd/mod.rs

@@ -580,7 +580,15 @@ extern "C" {
     pub fn abs(i: ::c_int) -> ::c_int;
     pub fn atof(s: *const ::c_char) -> ::c_double;
     pub fn labs(i: ::c_long) -> ::c_long;
+    #[cfg_attr(
+        all(target_os = "freebsd", any(freebsd12, freebsd11, freebsd10)),
+        link_name = "rand@FBSD_1.0"
+    )]
     pub fn rand() -> ::c_int;
+    #[cfg_attr(
+        all(target_os = "freebsd", any(freebsd12, freebsd11, freebsd10)),
+        link_name = "srand@FBSD_1.0"
+    )]
     pub fn srand(seed: ::c_uint);
 
     pub fn getifaddrs(ifap: *mut *mut ::ifaddrs) -> ::c_int;