raw string literal not handled

[matthiaskrgr]

cppcheck throws an error on this code:

const char IncludeRegexPattern[] =   R"(^[\t\ ]*#[\t\ ]*(import|include)[^"<]*(["<][^">]*[">]))";

code from https://github.com/llvm-mirror/clang/blob/2e23251/lib/Format/Format.cpp#L1317