Depending on the specific PHP configuration, the regex matching for the
version number in get_zlib_version() can fail.
On master, this results in deprecation warnings and subsequent test
borks:
```
Deprecated: version_compare(): Passing null to parameter #1 ($version1) of type string is deprecated in /work/php-src/ext/zlib/tests/gzgetc_basic.skip.php on line 3 [/work/php-src/ext/zlib/tests/gzgetc_basic.phpt]
Deprecated: version_compare(): Passing null to parameter #1 ($version1) of type string is deprecated in /work/php-src/ext/zlib/tests/gzgetc_basic_1.skip.php on line 4
```
Since ZLIB_VERSION is a constant containing the version as a string,
remove all this nonsense and just use the constant directly.
Depending on the specific PHP configuration, the regex matching for the version number in get_zlib_version() can fail.
On master, this results in deprecation warnings and subsequent test borks:
Since ZLIB_VERSION is a constant containing the version as a string, remove all this nonsense and just use the constant directly.
Found whilst working on my analyzer.