Add C++

[johnsaigle]

https://snyk.io/blog/top-5-c-security-risks/
https://snyk.io/blog/unintimidating-intro-to-c-cpp-vulnerabilities/
https://snyk.io/blog/exploring-3-types-of-directory-traversal-vulnerabilities-in-c-c/

e.g.
printf
gets
...
and more classics

It might be good to structure this to be non-overlapping with the C wordlist. It would be possible to audit a C++ project by concatenating some combination of C and C++ lists that way