[PathV2]: Fix bug in create_directories which caused infinite recursion on
som inputs.

Bug found and fix proposed by Kal Conley!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153225 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/PathV2.cpp b/lib/Support/PathV2.cpp
index 786e1a1..e2a69a6 100644
--- a/lib/Support/PathV2.cpp
+++ b/lib/Support/PathV2.cpp
@@ -654,12 +654,13 @@
   StringRef p = path.toStringRef(path_storage);
 
   StringRef parent = path::parent_path(p);
-  bool parent_exists;
+  if (!parent.empty()) {
+    bool parent_exists;
+    if (error_code ec = fs::exists(parent, parent_exists)) return ec;
 
-  if (error_code ec = fs::exists(parent, parent_exists)) return ec;
-
-  if (!parent_exists)
-    if (error_code ec = create_directories(parent, existed)) return ec;
+    if (!parent_exists)
+      if (error_code ec = create_directories(parent, existed)) return ec;
+  }
 
   return create_directory(p, existed);
 }