Remove unused using statement.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@207427 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index 7416987..009b200 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -51,7 +51,6 @@
 using namespace clang;
 
 using llvm::TimeRecord;
-using llvm::make_unique;
 
 namespace {
   class SimpleTimer {