Require rust >= 1.40 and drop libc_non_exhaustive conditional

[ resolve conflicts - Trevor ]

build.rs

@@ -18,7 +18,6 @@ const ALLOWED_CFGS: &'static [&'static str] = &[
     "libc_const_extern_fn_unstable",
     "libc_deny_warnings",
     "libc_long_array",
-    "libc_non_exhaustive",
     "libc_ptr_addr_of",
     "libc_thread_local",
     "libc_underscore_const_names",
@@ -83,11 +82,6 @@ fn main() {
         set_cfg("libc_deny_warnings");
     }
 
-    // Rust >= 1.40 supports #[non_exhaustive].
-    if rustc_minor_ver >= 40 || rustc_dep_of_std {
-        set_cfg("libc_non_exhaustive");
-    }
-
     // Rust >= 1.47 supports long array:
     if rustc_minor_ver >= 47 || rustc_dep_of_std {
         set_cfg("libc_long_array");

src/unix/linux_like/linux/mod.rs

@@ -953,6 +953,14 @@ s! {
         pub pid: ::c_int,
     }
 
+    // linux/openat2.h
+    #[non_exhaustive]
+    pub struct open_how {
+        pub flags: ::__u64,
+        pub mode: ::__u64,
+        pub resolve: ::__u64,
+    }
+
     #[repr(align(8))]
     pub struct tpacket_rollover_stats {
         pub tp_all: ::__u64,
@@ -6183,10 +6191,3 @@ cfg_if! {
 
 mod arch;
 pub use self::arch::*;
-
-cfg_if! {
-    if #[cfg(libc_non_exhaustive)] {
-        mod non_exhaustive;
-        pub use self::non_exhaustive::*;
-    }
-}