Retire llvm::alignOf in favor of C++11 alignof.

No functionality change intended.

llvm-svn: 284733
diff --git a/llvm/lib/IR/User.cpp b/llvm/lib/IR/User.cpp
index a75abe6..497b4aa 100644
--- a/llvm/lib/IR/User.cpp
+++ b/llvm/lib/IR/User.cpp
@@ -43,10 +43,9 @@
 void User::allocHungoffUses(unsigned N, bool IsPhi) {
   assert(HasHungOffUses && "alloc must have hung off uses");
 
-  static_assert(AlignOf<Use>::Alignment >= AlignOf<Use::UserRef>::Alignment,
+  static_assert(alignof(Use) >= alignof(Use::UserRef),
                 "Alignment is insufficient for 'hung-off-uses' pieces");
-  static_assert(AlignOf<Use::UserRef>::Alignment >=
-                    AlignOf<BasicBlock *>::Alignment,
+  static_assert(alignof(Use::UserRef) >= alignof(BasicBlock *),
                 "Alignment is insufficient for 'hung-off-uses' pieces");
 
   // Allocate the array of Uses, followed by a pointer (with bottom bit set) to