Recover some overzealously removed includes.

llvm-svn: 320648
diff --git a/llvm/lib/Support/Allocator.cpp b/llvm/lib/Support/Allocator.cpp
index 310f616..f48edac 100644
--- a/llvm/lib/Support/Allocator.cpp
+++ b/llvm/lib/Support/Allocator.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/raw_ostream.h"
 
 namespace llvm {