Fixes a bug when iterating on paths

This fixes the incorrect implementation of iterating on file/directory
paths.

Differential Review: http://llvm-reviews.chandlerc.com/D1277


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188183 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/Path.cpp

@@ -77,7 +77,7 @@ namespace {
       return path.substr(0, 1);
 
     // * {file,directory}name
-    size_t end = path.find_first_of(separators, 2);
+    size_t end = path.find_first_of(separators);
     return path.substr(0, end);
   }