[OpenCL] Adding reserved operator logical xor for OpenCL

This patch adds the reserved operator ^^ when compiling for OpenCL (spec v1.1 s6.3.g),
which results in a more meaningful error message.

Patch by Neil Hickey!

Review: http://reviews.llvm.org/D13280

M    test/SemaOpenCL/unsupported.cl
M    include/clang/Basic/TokenKinds.def
M    include/clang/Basic/DiagnosticParseKinds.td
M    lib/Basic/OperatorPrecedence.cpp
M    lib/Lex/Lexer.cpp
M    lib/Parse/ParseExpr.cpp

llvm-svn: 259651
diff --git a/clang/lib/Basic/OperatorPrecedence.cpp b/clang/lib/Basic/OperatorPrecedence.cpp
index ade8d6d..384d23c 100644
--- a/clang/lib/Basic/OperatorPrecedence.cpp
+++ b/clang/lib/Basic/OperatorPrecedence.cpp
@@ -53,6 +53,7 @@
   case tok::pipeequal:            return prec::Assignment;
   case tok::question:             return prec::Conditional;
   case tok::pipepipe:             return prec::LogicalOr;
+  case tok::caretcaret:
   case tok::ampamp:               return prec::LogicalAnd;
   case tok::pipe:                 return prec::InclusiveOr;
   case tok::caret:                return prec::ExclusiveOr;