[Async CC] Fixed AuthInfo of AsyncCallEmission.

Previously, an empty PtrAuthInfo was used to construct a FunctionPointer
in AsyncCallEmission::getCalleeFunctionPointer.  Here that is corrected
to use the auth info that was attached to the callee function pointer
(which is actually a pointer to an AsyncFunctionPointer struct).

Author: nate-chandler

lib/IRGen/GenCall.cpp

@@ -2350,7 +2350,8 @@ class AsyncCallEmission final : public CallEmission {
   }
   FunctionPointer getCalleeFunctionPointer() override {
     return FunctionPointer(
-        FunctionPointer::KindTy::Function, calleeFunction, PointerAuthInfo(),
+        FunctionPointer::KindTy::Function, calleeFunction,
+        CurCallee.getFunctionPointer().getAuthInfo(),
         IGF.IGM.getSignature(getCallee().getSubstFunctionType()));
   }
   SILType getParameterType(unsigned index) override {