[libclang] Add logging for clang_createTranslationUnit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182682 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index bd20800..dbef620 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -2544,9 +2544,13 @@
   
 CXTranslationUnit clang_createTranslationUnit(CXIndex CIdx,
                                               const char *ast_filename) {
-  if (!CIdx)
+  if (!CIdx || !ast_filename)
     return 0;
 
+  LOG_FUNC_SECTION {
+    *Log << ast_filename;
+  }
+
   CIndexer *CXXIdx = static_cast<CIndexer *>(CIdx);
   FileSystemOptions FileSystemOpts;