Add test for --remap-path-prefix on std imports

Author: cbeuw

src/test/codegen/remap_path_prefix/issue-73167-remap-std.rs

@@ -0,0 +1,12 @@
+// ignore-windows
+
+// compile-flags: -g  -C no-prepopulate-passes --remap-path-prefix=/=/the/root/
+
+// Here we check that imported code from std has their path remapped
+
+// CHECK: !DIFile(filename: "{{/the/root/.*/library/std/src/panic.rs}}"
+fn main() {
+    std::thread::spawn(|| {
+        println!("hello");
+    });
+}