Update coding standards wrt. C99?

Hi all, since master requires (mostly) C99 compliant compilers anyway, I wonder if we like to update our coding standards[1], to reflect: * that we require (mostly) C99 compliant compilers (instead of ANSI-C compliant compilers) * that mixing of declarations and statements is fine * that C++ style comments are now allowed, or maybe that they are still forbidden (in the latter case the stated reasons should be updated) We may also consider to drop the "Documentation and folding hooks"[2] section; besides that it is already partially outdated (AIUI, doc/genfuncsummary is superseeded by doc/docgen for a long time), I don't think these folding markers encapsulating each individual function are useful nowadays. Thoughts? [1] <https://github.com/php/php-src/blob/master/CODING_STANDARDS.md> [2] <https://github.com/php/php-src/blob/master/CODING_STANDARDS.md#documentation-and-folding-hooks> -- Christoph M. Becker