Remove unnecessary comments

Author: fpasserby

clang/test/CodeGenCoroutines/coro-symmetric-transfer-01.cpp

@@ -47,7 +47,6 @@ detached_task foo() {
   co_return;
 }
 
-// FIXME: is this test needed now?
 // check that the lifetime of the coroutine handle used to obtain the address is contained within single basic block, and hence does not live across suspension points.
 // CHECK-LABEL: final.suspend:
 // CHECK:         %{{.+}} = call token @llvm.coro.save(ptr null)

clang/test/CodeGenCoroutines/pr59181.cpp

@@ -48,8 +48,6 @@ void foo() {
   bar(true);
 }
 
-// FIXME: the test doesn't seem to be relevant anymore,
-// because objects that require cleanup are no more emitted in the suspend block
 // CHECK: cleanup.cont:{{.*}}
 // CHECK-NEXT: load i8
 // CHECK-NEXT: trunc

llvm/lib/Transforms/Coroutines/CoroSplit.cpp

@@ -169,6 +169,8 @@ class CoroCloner {
 
 // FIXME:
 // Lower the intrinisc earlier if coroutine frame doesn't escape
+// and it is known that other transformations, for example, sanitizers
+// won't lead to incorrect code.
 static void lowerAwaitSuspend(IRBuilder<> &Builder, CoroAwaitSuspendInst *CB) {
   auto Wrapper = CB->getWrapperFunction();
   auto Awaiter = CB->getAwaiter();