[php-src] Issue #9446: declare statement is not scoped when using curly braces

Issue: https://github.com/php/php-src/issues/9446 Author: dingo-d ### Description When writing tests for phpcs sniff using [some useful helpers](https://github.com/PHPCSStandards/PHPCSUtils/issues/339) regarding declare statements, I came up with an unusual behavior of the declare statements, when braces are used. I was testing out a code that looked like this: ```php <?php declare(strict_types=1) echo 'hi!'; { // Code. } ``` that threw a [fatal error](https://3v4l.org/9WLmh) because you cannot use curly braces with strict_types directive or alternative control structure syntax (declare: ... enddeclare;) So I tried to see what will happen if I use a directive that allows the use of curly braces, like encoding. So I tried: ```php <?php declare(encoding='ISO-8859-15') echo 'aäaß' . "\n"; { echo 'aäaß' . "\n"; } ``` And I got out: ```bash aÀaà aÀaà ``` I thought I'd get a parse error like when you omit the : when using if with endif; statement. Although, when testing the if statement with the curly braces, like in the example above, I can also see the echoed value before the condition, so I guess that's kinda expected. What was a buggy behavior was this: ```php <?php declare(encoding='ISO-8859-15') { echo 'aäaß' . "\n"; } echo 'aäaß' . "\n"; ``` I expected to see ```bash aÀaà aäaß ``` But I got (again) ```bash aÀaà aÀaà ``` So it seems that the declare statement, no matter if we are using curly braces, or alternative control structure syntax, will be applied throughout the file, instead of being scoped. ### PHP Version PHP 7.4.26 ### Operating System Ubuntu 20.04 (on WSL)