Media: Use version_compare() for Imagick version check when removing alpha.

Previously `remove_pdf_alpha_channel()` used `Imagick::getVersion()` to validate the environment is capable of handling alpha. This was the incorrect function to use to check the module version as it will only provide the ImageMagick API version. This patch adjusts to instead use `phpversion()` as this is the correct method to get the Imagick version needed to determine alpha compatibility. This fixes a number of host tests that have been correctly failing on subsets of environments. Serendipidously, sometimes the API version was high enough to avoid shining light on this problem.

Props swissspidy, joedolson, antpb.
Fixes #60798.


git-svn-id: https://develop.svn.wordpress.org/trunk@58415 602fd350-edb4-49c9-b593-d223f7449a82

Author: antpb

src/wp-includes/class-wp-image-editor-imagick.php

@@ -775,9 +775,8 @@ public function save( $destfilename = null, $mime_type = null ) {
 	 * @since 6.4.0
 	 */
 	protected function remove_pdf_alpha_channel() {
-		$version = Imagick::getVersion();
 		// Remove alpha channel if possible to avoid black backgrounds for Ghostscript >= 9.14. RemoveAlphaChannel added in ImageMagick 6.7.5.
-		if ( $version['versionNumber'] >= 0x675 ) {
+		if ( version_compare( phpversion( 'imagick' ), '9.14', '>=' ) ) {
 			try {
 				// Imagick::ALPHACHANNEL_REMOVE mapped to RemoveAlphaChannel in PHP imagick 3.2.0b2.
 				$this->image->setImageAlphaChannel( defined( 'Imagick::ALPHACHANNEL_REMOVE' ) ? Imagick::ALPHACHANNEL_REMOVE : 12 );