Temporarily disable the test call to rust_begin_unwind

Since [1] this symbol is mangled, meaning it is not easy to call
directly. A better fix will come in [2] but for now, just disable that
portion of the test.

[1]: rust-lang#127173
[2]: rust-lang/compiler-builtins#802

Author: tgross35

compiler-builtins/builtins-test-intrinsics/src/main.rs

@@ -626,13 +626,14 @@ fn run() {
 
     something_with_a_dtor(&|| assert_eq!(bb(1), 1));
 
-    extern "C" {
-        fn rust_begin_unwind(x: usize);
-    }
-
-    unsafe {
-        rust_begin_unwind(0);
-    }
+    // FIXME(#802): This should be re-enabled once a workaround is found.
+    // extern "C" {
+    //     fn rust_begin_unwind(x: usize);
+    // }
+
+    // unsafe {
+    //     rust_begin_unwind(0);
+    // }
 }
 
 fn something_with_a_dtor(f: &dyn Fn()) {