Update prebuilt Clang to r416183b from Android.

https://android.googlesource.com/platform/prebuilts/clang/host/
linux-x86/+/06a71ddac05c22edb2d10b590e1769b3f8619bef

clang 12.0.5 (based on r416183b) from build 7284624.

Change-Id: I277a316abcf47307562d8b748b84870f31a72866
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/linux-x64/clang/include/llvm/ADT/PostOrderIterator.h b/linux-x64/clang/include/llvm/ADT/PostOrderIterator.h
index 2fe7447..bb413a9 100644
--- a/linux-x64/clang/include/llvm/ADT/PostOrderIterator.h
+++ b/linux-x64/clang/include/llvm/ADT/PostOrderIterator.h
@@ -18,6 +18,7 @@
 #include "llvm/ADT/GraphTraits.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/iterator_range.h"
 #include <iterator>
 #include <set>
@@ -101,7 +102,7 @@
 
   // VisitStack - Used to maintain the ordering.  Top = current block
   // First element is basic block pointer, second is the 'next child' to visit
-  std::vector<std::pair<NodeRef, ChildItTy>> VisitStack;
+  SmallVector<std::pair<NodeRef, ChildItTy>, 8> VisitStack;
 
   po_iterator(NodeRef BB) {
     this->insertEdge(Optional<NodeRef>(), BB);