really check if mod_deflate is loaded

lib/minimizer.php

@@ -33,7 +33,7 @@ abstract class OC_Minimizer {
 		// on some systems (e.g. SLES 11, but not Ubuntu) mod_deflate and zlib compression will compress the output twice.
 		// This results in broken core.css and  core.js. To avoid it, we switch off zlib compression.
 		// Since mod_deflate is still active, Apache will compress what needs to be compressed, i.e. no disadvantage.
-		if(function_exists('apache_setenv') && ini_get('zlib.output_compression')) {
+		if(function_exists('apache_get_modules') && ini_get('zlib.output_compression') && in_array('mod_deflate', apache_get_modules())) {
 			ini_set('zlib.output_compression', 'Off');
 		}
 		if ($encoding = OC_Request::acceptGZip()) {