[clang-format] Adds a canonical delimiter to raw string formatting

Summary:
This patch adds canonical delimiter support to the raw string formatting.
This allows matching delimiters to be updated to the canonical one.

Reviewers: bkramer

Reviewed By: bkramer

Subscribers: klimek, cfe-commits

Differential Revision: https://reviews.llvm.org/D42187

llvm-svn: 322956
diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
index 88c90a8..0da0cea 100644
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -459,6 +459,7 @@
     IO.mapOptional("Language", Format.Language);
     IO.mapOptional("Delimiters", Format.Delimiters);
     IO.mapOptional("EnclosingFunctions", Format.EnclosingFunctions);
+    IO.mapOptional("CanonicalDelimiter", Format.CanonicalDelimiter);
     IO.mapOptional("BasedOnStyle", Format.BasedOnStyle);
   }
 };
@@ -713,6 +714,7 @@
            "PARSE_TEXT_PROTO",
            "ParseTextProto",
        },
+      /*CanonicalDelimiter=*/"",
       /*BasedOnStyle=*/"google",
   }};
   GoogleStyle.SpacesBeforeTrailingComments = 2;