Fix longjmp-across-rust test

Destructor are removed from stack because it's considered UB.

Author: nbdd0121

tests/run-make/longjmp-across-rust/main.rs

@@ -10,19 +10,11 @@ fn main() {
 }
 }
 
-structA;
-
-implDropforA{
-fndrop(&mutself){}
-}
-
 extern"C"fntest_middle(){
-let _a = A;
 foo();
 }
 
 fnfoo(){
-let _a = A;
 unsafe{
 test_end();
 }