We need this as the rust-installer tool would otherwise
generate corrupt tarballs on big endian targets. This
matters when generating bootstrap tar.xz tarballs.

From f01c8060310ab3456f93567cb819384c4ae4e117 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Thu, 22 Aug 2019 22:46:47 -0700
Subject: [PATCH] Fix tests on big-endian targets

Turns out liblzma wants to be compiled with options to indicate that
it's big endian!
---
 lzma-sys/build.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lzma-sys/build.rs b/lzma-sys/build.rs
index 7366d9c..a1e28b4 100644
--- a/vendor/lzma-sys/build.rs
+++ b/vendor/lzma-sys/build.rs
@@ -56,6 +56,12 @@ fn main() {
         build.flag("-std=c99").flag("-pthread");
     }
 
+    if let Ok(s) = env::var("CARGO_CFG_TARGET_ENDIAN") {
+        if s == "big" {
+            build.define("WORDS_BIGENDIAN", None);
+        }
+    }
+
     build.compile("liblzma.a");
 }