[Coroutines] Fix a few failing tests

[lxfind]

Summary

https://reviews.llvm.org/D82029 introduced the non-throw check for final_suspend(). There are a few tests I missed in that patch.
Fixing them here.

[lxfind]

Address lint message

[lxfind]

Rebase. Fix two more tests.

libcxx/test/std/experimental/language.support/support.coroutines/end.to.end/fullexpr-dtor.pass.cpp

 struct Bug {
   bool await_ready() { return true; }
   void await_suspend(std::experimental::coroutine_handle<>) {}
   Noisy await_resume() { return {}; }
 };
 struct coro2 {
   struct promise_type {
     suspend_never initial_suspend() { return{}; }
-    suspend_never final_suspend() noexcept { return{}; }
+    suspend_never final_suspend() noexcept { return {}; }
     coro2 get_return_object() { return{}; }
     void return_void() {}
     Bug yield_value(int) { return {}; }
     void unhandled_exception() {}
   };
 };
 
 // Checks that destructors are correctly invoked for the object returned by

libcxx/test/std/experimental/language.support/support.coroutines/end.to.end/go.pass.cpp

static void run_one()
     stack[--count]();
   }
 
   struct promise_type
   {
     suspend_never initial_suspend() {
       return {};
     }
-    suspend_never final_suspend() noexcept {
-      return {};
-    }
+    suspend_never final_suspend() noexcept { return {}; }
     void return_void() {}
     goroutine get_return_object() {
       return{};
     }
     void unhandled_exception() {}
   };
 };
 int goroutine::count;

libcxx/test/std/experimental/language.support/support.coroutines/end.to.end/multishot_func.pass.cpp

 template <typename R> struct func {
   struct Input {R a, b;};
 
   struct promise_type {
     Input* I;
     R result;
     func get_return_object() { return {this}; }
     suspend_always initial_suspend() { return {}; }
-    suspend_never final_suspend() { return {}; }
+    suspend_never final_suspend() noexcept { return {}; }
     void return_void() {}
     template <typename F>
     suspend_always yield_value(F&& f) {
       result = f(I->a, I->b);
       return {};
     }
     void unhandled_exception() {}
   };

libcxx/test/std/experimental/language.support/support.coroutines/end.to.end/oneshot_func.pass.cpp

 // This file tests, one shot, movable std::function like thing using coroutine
 // for compile-time type erasure and unerasure.
 
 template <typename R> struct func {
   struct promise_type {
     R result;
     func get_return_object() { return {this}; }
     suspend_always initial_suspend() { return {}; }
-    suspend_always final_suspend() { return {}; }
+    suspend_always final_suspend() noexcept { return {}; }
     void return_value(R v) { result = v; }
     void unhandled_exception() {}
   };
 
   R operator()() {
     h.resume();
     R result = h.promise().result;
     h.destroy();