[clang-format] Do not format raw string literals inside a recognized function with a non-recognized delimiter

Summary:
This stops clang-format from touching raw string contents with unrecognized delimiters inside recognized functions.
Unrecognized delimiters signal that the string might be special.

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D48728

llvm-svn: 335876
diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index 1a5a6de..bb8efd6 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -1648,7 +1648,7 @@
   if (!Delimiter)
     return None;
   auto RawStringStyle = RawStringFormats.getDelimiterStyle(*Delimiter);
-  if (!RawStringStyle)
+  if (!RawStringStyle && Delimiter->empty())
     RawStringStyle = RawStringFormats.getEnclosingFunctionStyle(
         getEnclosingFunctionName(Current));
   if (!RawStringStyle)