drop more llvm:: prefixes on OwningPtr<>

More cleanup after r149798.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150379 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndexUSRs.cpp b/tools/libclang/CIndexUSRs.cpp
index f550394..690e84f 100644
--- a/tools/libclang/CIndexUSRs.cpp
+++ b/tools/libclang/CIndexUSRs.cpp
@@ -30,7 +30,7 @@
 
 namespace {
 class USRGenerator : public DeclVisitor<USRGenerator> {
-  llvm::OwningPtr<llvm::SmallString<128> > OwnedBuf;
+  OwningPtr<llvm::SmallString<128> > OwnedBuf;
   SmallVectorImpl<char> &Buf;
   llvm::raw_svector_ostream Out;
   bool IgnoreResults;