Auto merge of #38726 - japaric:sparc64, r=sanxiyn

sparc64-linux support

This is built on top of #38656 and depends on rust-lang/libc#483

Hello world works.

The libc-test test suite passes.

`panic!` doesn't fully work:

```
$ qemu-sparc64-static ./panic
thread 'main' panicked at 'explicit panic', panic.rs:1
note: Run with `RUST_BACKTRACE=1` for a backtrace.
Illegal instruction (core dumped)
```

Backtraces don't work either, probably related to the previous point:

```
$ export RUST_BACKTRACE=1
$ qemu-sparc64-static ./panic
thread 'main' panicked at 'explicit panic', panic.rs:1
stack backtrace:
Illegal instruction (core dumped)
```

r? @alexcrichton

@jakllsch Does panicking / backtraces work on sparc64-netbsd?

cc @glaubitz

2 files changed, 9 insertions, 6 deletions

diff --git a/src/libstd/env.rs b/src/libstd/env.rs
index 0521f301321..d843d97420a 100644
--- a/src/libstd/env.rs
+++ b/src/libstd/env.rs
@@ -712,6 +712,7 @@ pub mod consts {
     /// - powerpc
     /// - powerpc64
     /// - s390x
+    /// - sparc64
     #[stable(feature = "env", since = "1.0.0")]
     pub const ARCH: &'static str = super::arch::ARCH;
 
@@ -843,6 +844,11 @@ mod arch {
     pub const ARCH: &'static str = "s390x";
 }
 
+#[cfg(target_arch = "sparc64")]
+mod arch {
+    pub const ARCH: &'static str = "sparc64";
+}
+
 #[cfg(target_arch = "le32")]
 mod arch {
     pub const ARCH: &'static str = "le32";
diff --git a/src/libstd/os/linux/raw.rs b/src/libstd/os/linux/raw.rs
index 7c9274d0601..bb1830a147e 100644
--- a/src/libstd/os/linux/raw.rs
+++ b/src/libstd/os/linux/raw.rs
@@ -157,12 +157,9 @@ mod arch {
     }
 }
 
-#[cfg(target_arch = "mips64")]
-mod arch {
-    pub use libc::{off_t, ino_t, nlink_t, blksize_t, blkcnt_t, stat, time_t};
-}
-
-#[cfg(target_arch = "s390x")]
+#[cfg(any(target_arch = "mips64",
+          target_arch = "s390x",
+          target_arch = "sparc64"))]
 mod arch {
     pub use libc::{off_t, ino_t, nlink_t, blksize_t, blkcnt_t, stat, time_t};
 }