No longer allow block mode for declare(encoding)

Hi all, recently, there was a bug report regarding declare(encoding)[1]. I've checked that, and found that the current implementation of declare(encoding) doesn't make sense regarding "block mode", since this is completely ignored; instead, each (allowed) declare(encoding) works from where it is written till the next declare(encoding) (well, probably more or less). Since I consider switching the character encoding in the middle of a file not reasonable (and it might be hard to properly implement support for that), I suggest to disallow block mode for declare(encoding) as of PHP 8.3. A respective PR is available[2]. Thoughts? [1] <https://github.com/php/php-src/issues/9446> [2] <https://github.com/php/php-src/pull/9455> -- Christoph M. Becker