Add test for issue-37433

Author: JohnTitor

src/test/ui/issues/issue-37433.rs

@@ -0,0 +1,8 @@
+#![feature(asm)]
+
+fn main() {
+    unsafe {
+        asm!("" :: "r"(""));
+        //~^ ERROR: invalid value for constraint in inline assembly
+    }
+}

src/test/ui/issues/issue-37433.stderr

@@ -0,0 +1,8 @@
+error[E0669]: invalid value for constraint in inline assembly
+  --> $DIR/issue-37433.rs:5:24
+   |
+LL |         asm!("" :: "r"(""));
+   |                        ^^
+
+error: aborting due to previous error
+