Zend: add test for reading $http_response_header without explicit assignment which triggers deprecation warning

[LamentXU123]

implement test case as per the TODO message
https://github.com/php/php-src/blob/master/Zend/zend_compile.c#L2974-L2983

[Girgias]

This should be with all the other tests in ext/standard/tests/http/. But does this actually increase code coverage? There are a few tests already and I wasn't sure if I was hitting this code path.

[Girgias]

So the current line is indeed not covered by a unit test: https://app.codecov.io/github/php/php-src/blob/master/Zend%2Fzend_compile.c#L2978

[LamentXU123]

Weird. It is touching https://github.com/php/php-src/blob/master/Zend/zend_compile.c#L2931 instead of https://github.com/php/php-src/blob/master/Zend/zend_compile.c#L2979. Let me fix this.

[LamentXU123]

Fine, the new test should work
In original test cases deprecation is thrown directly in zend_try_compile_cv, this PR introduce a func that fails zend_try_compile_cv and therefore touch the other deprecation logic.

[Girgias]

Incredibly clever test :)