Implements UseTab for clang-format.

This is required for kernel linux kernel style formatting.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181693 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/WhitespaceManager.h b/lib/Format/WhitespaceManager.h
index 5f3dc55..1b24b3f 100644
--- a/lib/Format/WhitespaceManager.h
+++ b/lib/Format/WhitespaceManager.h
@@ -78,6 +78,8 @@
                              unsigned WhitespaceStartColumn,
                              unsigned EscapedNewlineColumn);
 
+  std::string getIndentText(unsigned Spaces);
+
   /// \brief Structure to store tokens for later layout and alignment.
   struct StoredToken {
     StoredToken(SourceLocation ReplacementLoc, unsigned ReplacementLength,