Don't set TARGET for non run-make tests

If something like this is needed again in the future, please set environment
variables for the build and run subprocesses, instead of setting them on the
compiletest process.

Author: Zalathar

src/tools/compiletest/src/lib.rs

@@ -525,11 +525,6 @@ fn run_tests(config: Arc<Config>) {
     // SAFETY: at this point we're still single-threaded.
     unsafe { env::set_var("__COMPAT_LAYER", "RunAsInvoker") };
 
-    // Let tests know which target they're running as.
-    //
-    // SAFETY: at this point we're still single-threaded.
-    unsafe { env::set_var("TARGET", &config.target) };
-
     let mut configs = Vec::new();
     if let TestMode::DebugInfo = config.mode {
         // Debugging emscripten code doesn't make sense today