complete openbsd support for std::env

- add `std::env:consts`
- deprecating `std::os::consts`
- refactoring errno_location()

src/libstd/env.rs

@@ -562,6 +562,38 @@ pub mod consts {
     pub const EXE_EXTENSION: &'static str = "";
 }
 
+/// Constants associated with the current target
+#[cfg(target_os = "openbsd")]
+pub mod consts {
+    pub use super::arch_consts::ARCH;
+
+    pub const FAMILY: &'static str = "unix";
+
+    /// A string describing the specific operating system in use: in this
+    /// case, `dragonfly`.
+    pub const OS: &'static str = "openbsd";
+
+    /// Specifies the filename prefix used for shared libraries on this
+    /// platform: in this case, `lib`.
+    pub const DLL_PREFIX: &'static str = "lib";
+
+    /// Specifies the filename suffix used for shared libraries on this
+    /// platform: in this case, `.so`.
+    pub const DLL_SUFFIX: &'static str = ".so";
+
+    /// Specifies the file extension used for shared libraries on this
+    /// platform that goes after the dot: in this case, `so`.
+    pub const DLL_EXTENSION: &'static str = "so";
+
+    /// Specifies the filename suffix used for executable binaries on this
+    /// platform: in this case, the empty string.
+    pub const EXE_SUFFIX: &'static str = "";
+
+    /// Specifies the file extension, if any, used for executable binaries
+    /// on this platform: in this case, the empty string.
+    pub const EXE_EXTENSION: &'static str = "";
+}
+
 /// Constants associated with the current target
 #[cfg(target_os = "android")]
 pub mod consts {

src/libstd/os.rs

@@ -1289,6 +1289,8 @@ pub mod consts {
 }
 
 #[cfg(target_os = "openbsd")]
+#[deprecated(since = "1.0.0", reason = "renamed to env::consts")]
+#[unstable(feature = "os")]
 pub mod consts {
     pub use os::arch_consts::ARCH;
 

src/libstd/sys/unix/os.rs

@@ -47,13 +47,9 @@ pub fn errno() -> i32 {
     }
 
     #[cfg(target_os = "openbsd")]
-    fn errno_location() -> *const c_int {
-        extern {
-            fn __errno() -> *const c_int;
-        }
-        unsafe {
-            __errno()
-        }
+    unsafe fn errno_location() -> *const c_int {
+        extern { fn __errno() -> *const c_int; }
+        __errno()
     }
 
     #[cfg(any(target_os = "linux", target_os = "android"))]