Remove useless 'llvm::' qualifier from names like StringRef and others that are
brought into 'clang' namespace by clang/Basic/LLVM.h

llvm-svn: 172323
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 35a9aa4..a958fd9 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -155,7 +155,7 @@
   }
 }
 
-static void setPreambleFile(const ASTUnit *AU, llvm::StringRef preambleFile) {
+static void setPreambleFile(const ASTUnit *AU, StringRef preambleFile) {
   getOnDiskData(AU).PreambleFile = preambleFile;
 }