Convert run-make/windows-spawn to rmake

tests/run-make/windows-spawn/Makefile

@@ -1,8 +0,0 @@
-include ../tools.mk
-
-# only-windows
-
-all:
-	$(RUSTC) -o "$(TMPDIR)/hopefullydoesntexist bar.exe" hello.rs
-	$(RUSTC) spawn.rs
-	$(TMPDIR)/spawn.exe

tests/run-make/windows-spawn/rmake.rs

@@ -0,0 +1,17 @@
+//@ only-windows
+
+use run_make_support::{run, rustc, tmp_dir};
+
+// On Windows `Command` uses `CreateProcessW` to run a new process.
+// However, in the past std used to not pass in the application name, leaving
+// `CreateProcessW` to use heuristics to guess the intended name from the
+// command line string. Sometimes this could go very wrong.
+// E.g. in Rust 1.0 `Command::new("foo").arg("bar").spawn()` will try to launch
+// `foo bar.exe` if foo.exe does not exist. Which is clearly not desired.
+
+fn main() {
+    let out_dir = tmp_dir();
+    rustc().input("hello.rs").output(out_dir.join("hopefullydoesntexist bar.exe")).run();
+    rustc().input("spawn.rs").run();
+    run("spawn");
+}

tests/run-make/windows-spawn/spawn.rs

@@ -3,10 +3,8 @@ use std::process::Command;
 
 fn main() {
     // Make sure it doesn't try to run "hopefullydoesntexist bar.exe".
-    assert_eq!(Command::new("hopefullydoesntexist")
-                   .arg("bar")
-                   .spawn()
-                   .unwrap_err()
-                   .kind(),
-               ErrorKind::NotFound);
+    assert_eq!(
+        Command::new("hopefullydoesntexist").arg("bar").spawn().unwrap_err().kind(),
+        ErrorKind::NotFound
+    )
 }