Change Function::getIntrinsicID() to return an Intrinsic::ID.  NFC.

Now that Intrinsic::ID is a typed enum, we can forward declare it and so return it from this method.

This updates all users which were either using an unsigned to store it, or had a now unnecessary cast.

llvm-svn: 237810
diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
index 8910564..43abdd2 100644
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -233,9 +233,8 @@
   // Upgrade intrinsic attributes.  This does not change the function.
   if (NewFn)
     F = NewFn;
-  if (unsigned id = F->getIntrinsicID())
-    F->setAttributes(Intrinsic::getAttributes(F->getContext(),
-                                              (Intrinsic::ID)id));
+  if (Intrinsic::ID id = F->getIntrinsicID())
+    F->setAttributes(Intrinsic::getAttributes(F->getContext(), id));
   return Upgraded;
 }