Somwhat subtle issues with raw string literals in C++

[Philipp Stephani]

Hi,

there still seem to be some subtle issues with detection of raw string literals. Unfortunately they are hard to reproduce. One example that fails (for me) with a recent master build is:

cd /tmp

wget https://raw.githubusercontent.com/google/protobuf/ef7894e2dc6d287419e42a4fdc52cdfedd386d16/conformance/conformance_test.cc

/path/to/emacs -Q +686 conformance_test.cc

Around that line the fontification of the raw string literals is wrong (quote characters are treated as string terminators), in other parts of the file the fontification is correct. This typically happens with files that contain many large raw string literals that contain quote characters.