Auto merge of #1040 - semarie:openbsd-fix, r=alexcrichton

Openbsd fix

put in several fixes for OpenBSD (one fix per commit).
testsuite ran on OpenBSD 6.3-current (upcoming 6.4)

```
RUNNING ALL TESTS
PASSED 6474 tests
```

Author: bors

libc-test/build.rs

@@ -538,12 +538,6 @@ fn main() {
             "KERN_USERMOUNT" |
             "KERN_ARND" if openbsd => true,
 
-            // These constants were added in OpenBSD 6.2
-            "EV_RECEIPT" | "EV_DISPATCH" if openbsd => true,
-
-            // These constants were added in OpenBSD 6.3
-            "MAP_STACK" if openbsd => true,
-
             // These are either unimplemented or optionally built into uClibc
             "LC_CTYPE_MASK" | "LC_NUMERIC_MASK" | "LC_TIME_MASK" | "LC_COLLATE_MASK" | "LC_MONETARY_MASK" | "LC_MESSAGES_MASK" |
             "MADV_MERGEABLE" | "MADV_UNMERGEABLE" | "MADV_HWPOISON" | "IPV6_ADD_MEMBERSHIP" | "IPV6_DROP_MEMBERSHIP" | "IPV6_MULTICAST_LOOP" | "IPV6_V6ONLY" |

src/unix/bsd/netbsdlike/mod.rs

@@ -57,15 +57,6 @@ s! {
         pub l_type: ::c_short,
         pub l_whence: ::c_short,
     }
-
-    #[repr(packed)]
-    pub struct arphdr {
-        pub ar_hrd: u16,
-        pub ar_pro: u16,
-        pub ar_hln: u8,
-        pub ar_pln: u8,
-        pub ar_op: u16,
-    }
 }
 
 pub const D_T_FMT: ::nl_item = 0;
@@ -430,10 +421,6 @@ pub const IPV6_RECVPKTINFO: ::c_int = 36;
 pub const IPV6_PKTINFO: ::c_int = 46;
 
 pub const TCP_NODELAY:    ::c_int = 0x01;
-pub const TCP_KEEPIDLE:   ::c_int = 3;
-pub const TCP_KEEPINTVL:  ::c_int = 5;
-pub const TCP_KEEPCNT:    ::c_int = 6;
-pub const TCP_KEEPINIT:   ::c_int = 7;
 
 pub const SOL_SOCKET: ::c_int = 0xffff;
 pub const SO_DEBUG: ::c_int = 0x01;

src/unix/bsd/netbsdlike/netbsd/mod.rs

@@ -318,6 +318,15 @@ s! {
         pub ipi_addr: ::in_addr,
         pub ipi_ifindex: ::c_uint,
     }
+
+    #[repr(packed)]
+    pub struct arphdr {
+        pub ar_hrd: u16,
+        pub ar_pro: u16,
+        pub ar_hln: u8,
+        pub ar_pln: u8,
+        pub ar_op: u16,
+    }
 }
 
 pub const AT_FDCWD: ::c_int = -100;
@@ -381,6 +390,11 @@ pub const IP_RECVPKTINFO: ::c_int = 26;
 pub const IPV6_JOIN_GROUP: ::c_int = 12;
 pub const IPV6_LEAVE_GROUP: ::c_int = 13;
 
+pub const TCP_KEEPIDLE:  ::c_int = 3;
+pub const TCP_KEEPINTVL: ::c_int = 5;
+pub const TCP_KEEPCNT:   ::c_int = 6;
+pub const TCP_KEEPINIT:  ::c_int = 7;
+
 pub const SOCK_CONN_DGRAM: ::c_int = 6;
 pub const SOCK_DCCP: ::c_int = SOCK_CONN_DGRAM;
 pub const SOCK_NOSIGPIPE: ::c_int = 0x40000000;

src/unix/bsd/netbsdlike/openbsdlike/mod.rs

@@ -193,6 +193,14 @@ s! {
         pub gid: ::gid_t,
         pub pid: ::pid_t,
     }
+
+    pub struct arphdr {
+        pub ar_hrd: u16,
+        pub ar_pro: u16,
+        pub ar_hln: u8,
+        pub ar_pln: u8,
+        pub ar_op: u16,
+    }
 }
 
 pub const UT_NAMESIZE: usize = 32;
@@ -579,6 +587,7 @@ pub const CTL_MACHDEP: ::c_int = 7;
 pub const CTL_DDB: ::c_int = 9;
 pub const CTL_VFS: ::c_int = 10;
 pub const CTL_MAXID: ::c_int = 11;
+pub const HW_NCPUONLINE: ::c_int = 25;
 pub const KERN_OSTYPE: ::c_int = 1;
 pub const KERN_OSRELEASE: ::c_int = 2;
 pub const KERN_OSREV: ::c_int = 3;
@@ -653,7 +662,8 @@ pub const KERN_PROC_VMMAP: ::c_int = 80;
 pub const KERN_GLOBAL_PTRACE: ::c_int = 81;
 pub const KERN_CONSBUFSIZE: ::c_int = 82;
 pub const KERN_CONSBUF: ::c_int = 83;
-pub const KERN_MAXID: ::c_int = 84;
+pub const KERN_AUDIO: ::c_int = 84;
+pub const KERN_MAXID: ::c_int = 85;
 pub const KERN_PROC_ALL: ::c_int = 0;
 pub const KERN_PROC_PID: ::c_int = 1;
 pub const KERN_PROC_PGRP: ::c_int = 2;

src/unix/bsd/netbsdlike/openbsdlike/openbsd/mod.rs

@@ -47,7 +47,7 @@ pub const IFF_LINK1: ::c_int = 0x2000; // per link layer defined bit
 pub const IFF_LINK2: ::c_int = 0x4000; // per link layer defined bit
 pub const IFF_MULTICAST: ::c_int = 0x8000; // supports multicast
 
-pub const SIGSTKSZ : ::size_t = 24576;
+pub const SIGSTKSZ : ::size_t = 28672;
 
 extern {
     pub fn accept4(s: ::c_int, addr: *mut ::sockaddr,