[rust] If $TMPDIR is unset, use $HOME/.tmp instead

This patch is needed because in sb2 the temp files written to /tmp
by rustc are no longer available when the linker tries to use them.
Work around the issue by setting $TMPDIR to $HOME/.tmp instead.
If $TMPDIR is already set, that value is used as expected.

0009-Relocate-unset-tmp.patch

@@ -0,0 +1,38 @@
+diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
+index dd9d277fb..160e472cf 100644
+--- a/compiler/rustc_codegen_ssa/src/back/link.rs
++++ b/compiler/rustc_codegen_ssa/src/back/link.rs
+@@ -48,7 +48,7 @@ use std::ffi::OsString;
+ use std::fs::{read, File, OpenOptions};
+ use std::io::{BufWriter, Write};
+ use std::ops::Deref;
+-use std::path::{Path, PathBuf};
++use std::path::{MAIN_SEPARATOR, Path, PathBuf};
+ use std::process::{ExitStatus, Output, Stdio};
+ use std::{env, fmt, fs, io, mem, str};
+
+@@ -95,11 +95,24 @@ pub fn link_binary<'a>(
+         });
+
+         if outputs.outputs.should_link() {
++            let mut clear_tmp = false;
++            if env::var_os("TMPDIR").is_none() && env::var_os("HOME").is_some() {
++                let home_tmp = env::var_os("HOME").unwrap();
++                let home_tmp = format!("{}{}{}", home_tmp.to_string_lossy(), MAIN_SEPARATOR, ".tmp");
++                env::set_var("TMPDIR", &home_tmp);
++                if !Path::new(&home_tmp).exists() {
++                    let _ = fs::create_dir_all(home_tmp);
++                }
++                clear_tmp = true;
++            }
+             let tmpdir = TempFileBuilder::new()
+                 .prefix("rustc")
+                 .tempdir()
+                 .unwrap_or_else(|error| sess.emit_fatal(errors::CreateTempDir { error }));
+             let path = MaybeTempDir::new(tmpdir, sess.opts.cg.save_temps);
++            if clear_tmp {
++                env::remove_var("TMP");
++            }
+             let output = out_filename(
+                 sess,
+                 crate_type,

rust.spec

@@ -77,6 +77,7 @@ Patch5: 0005-Provide-ENV-controls-to-bypass-some-sb2-calls-betwee.patch
 Patch6: 0006-Scratchbox2-needs-to-be-able-to-tell-cargo-the-defau.patch
 Patch7: 0007-Disable-aarch64-outline-atomics-for-now.patch
 Patch8: 0008-Revert-Use-statx-s-64-bit-times-on-32-bit-linux-gnu.patch
+Patch9: 0009-Relocate-unset-tmp.patch
 # This is the real rustc spec - the stub one appears near the end.
 %ifarch %ix86