Fix tests on FreeBSD 11

FreeBSD svn r262489 removed some *_MAXID definitions in sys/sysctl.h.  They never
should've been used outside of the FreeBSD base system anyway.  Mark them as
deprecated, hide them from the API docs, and disable their tests.

r273250 removed MAP_RENAME and MAP_NORESERVE, flags used by mmap(2), but old
binaries that use them will still work.  Suppress their test errors.

r294930 changed stack_t.ss_sp from a char* to a void*.  Suppress its test error.

libc-test/build.rs

@@ -361,6 +361,19 @@ fn main() {
             "QFMT_VFS_OLD" |
             "QFMT_VFS_V0" if mips && linux => true,
 
+            // These constants were removed in FreeBSD 11 (svn r273250) but will
+            // still be accepted and ignored at runtime.
+            "MAP_RENAME" |
+            "MAP_NORESERVE" if freebsd => true,
+
+            // These constants were removed in FreeBSD 11 (svn r262489),
+            // and they've never had any legitimate use outside of the
+            // base system anyway.
+            "CTL_MAXID" |
+            "KERN_MAXID" |
+            "HW_MAXID" |
+            "USER_MAXID" if freebsd => true,
+
             _ => false,
         }
     });
@@ -461,7 +474,9 @@ fn main() {
         // sigval is actually a union, but we pretend it's a struct
         (struct_ == "sigevent" && field == "sigev_value") ||
         // aio_buf is "volatile void*" and Rust doesn't understand volatile
-        (struct_ == "aiocb" && field == "aio_buf")
+        (struct_ == "aiocb" && field == "aio_buf") ||
+        // stack_t.ss_sp's type changed from FreeBSD 10 to 11 in svn r294930
+        (freebsd && struct_ == "stack_t" && field == "ss_sp")
     });
 
     cfg.skip_field(move |struct_, field| {

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

@@ -169,7 +169,6 @@ pub const CTL_HW: ::c_int = 6;
 pub const CTL_MACHDEP: ::c_int = 7;
 pub const CTL_USER: ::c_int = 8;
 pub const CTL_P1003_1B: ::c_int = 9;
-pub const CTL_MAXID: ::c_int = 10;
 pub const KERN_OSTYPE: ::c_int = 1;
 pub const KERN_OSRELEASE: ::c_int = 2;
 pub const KERN_OSREV: ::c_int = 3;
@@ -207,7 +206,6 @@ pub const KERN_LOGSIGEXIT: ::c_int = 34;
 pub const KERN_IOV_MAX: ::c_int = 35;
 pub const KERN_HOSTUUID: ::c_int = 36;
 pub const KERN_ARND: ::c_int = 37;
-pub const KERN_MAXID: ::c_int = 38;
 pub const KERN_PROC_ALL: ::c_int = 0;
 pub const KERN_PROC_PID: ::c_int = 1;
 pub const KERN_PROC_PGRP: ::c_int = 2;
@@ -254,7 +252,6 @@ pub const HW_DISKSTATS: ::c_int = 9;
 pub const HW_FLOATINGPT: ::c_int = 10;
 pub const HW_MACHINE_ARCH: ::c_int = 11;
 pub const HW_REALMEM: ::c_int = 12;
-pub const HW_MAXID: ::c_int = 13;
 pub const USER_CS_PATH: ::c_int = 1;
 pub const USER_BC_BASE_MAX: ::c_int = 2;
 pub const USER_BC_DIM_MAX: ::c_int = 3;
@@ -275,7 +272,6 @@ pub const USER_POSIX2_SW_DEV: ::c_int = 17;
 pub const USER_POSIX2_UPE: ::c_int = 18;
 pub const USER_STREAM_MAX: ::c_int = 19;
 pub const USER_TZNAME_MAX: ::c_int = 20;
-pub const USER_MAXID: ::c_int = 21;
 pub const CTL_P1003_1B_ASYNCHRONOUS_IO: ::c_int = 1;
 pub const CTL_P1003_1B_MAPPED_FILES: ::c_int = 2;
 pub const CTL_P1003_1B_MEMLOCK: ::c_int = 3;
@@ -301,6 +297,20 @@ pub const CTL_P1003_1B_SEM_NSEMS_MAX: ::c_int = 22;
 pub const CTL_P1003_1B_SEM_VALUE_MAX: ::c_int = 23;
 pub const CTL_P1003_1B_SIGQUEUE_MAX: ::c_int = 24;
 pub const CTL_P1003_1B_TIMER_MAX: ::c_int = 25;
+
+// The *_MAXID constants never should've been used outside of the
+// FreeBSD base system.  And with the exception of CTL_P1003_1B_MAXID,
+// they were all removed in svn r262489.  They remain here for backwards
+// compatibility only, and are scheduled to be removed in libc 1.0.0.
+#[doc(hidden)]
+pub const CTL_MAXID: ::c_int = 10;
+#[doc(hidden)]
+pub const KERN_MAXID: ::c_int = 38;
+#[doc(hidden)]
+pub const HW_MAXID: ::c_int = 13;
+#[doc(hidden)]
+pub const USER_MAXID: ::c_int = 21;
+#[doc(hidden)]
 pub const CTL_P1003_1B_MAXID: ::c_int = 26;
 
 pub const MSG_NOSIGNAL: ::c_int = 0x20000;

src/unix/bsd/freebsdlike/mod.rs

@@ -92,6 +92,7 @@ s! {
     }
 
     pub struct stack_t {
+        // In FreeBSD 11 and later, ss_sp is actually a void*
         pub ss_sp: *mut ::c_char,
         pub ss_size: ::size_t,
         pub ss_flags: ::c_int,