Add initgroups to BSD targets

Author: JayH5

src/unix/bsd/freebsdlike/mod.rs

@@ -964,6 +964,7 @@ extern {
     pub fn setutxent();
     pub fn setresgid(rgid: ::gid_t, egid: ::gid_t, sgid: ::gid_t) -> ::c_int;
     pub fn setresuid(ruid: ::uid_t, euid: ::uid_t, suid: ::uid_t) -> ::c_int;
+    pub fn initgroups(name: *const ::c_char, basegid: ::gid_t) -> ::c_int;
 }
 
 #[link(name = "util")]

src/unix/bsd/netbsdlike/mod.rs

@@ -616,6 +616,8 @@ extern {
     pub fn pthread_mutex_timedlock(lock: *mut pthread_mutex_t,
                                    abstime: *const ::timespec) -> ::c_int;
     pub fn pipe2(fds: *mut ::c_int, flags: ::c_int) -> ::c_int;
+
+    pub fn initgroups(name: *const ::c_char, basegid: ::gid_t) -> ::c_int;
 }
 
 cfg_if! {