added CentOS 8 detection to installer

Author: ms217

install/lib/install.lib.php

@@ -341,6 +341,15 @@ function get_distname() {
 				$distid = 'centos72';
 			}
 			swriteln("Operating System: CentOS $var\n");
+                } elseif(stristr($content, 'CentOS Linux release 8')) {
+                        $distname = 'CentOS';
+                        $distver = 'Unknown';
+                        $distbaseid = 'fedora';
+			$distid = 'centos80';
+                        $var=explode(" ", $content);
+                        $var=explode(".", $var[3]);
+                        $var=$var[0].".".$var[1];
+                        swriteln("Operating System: CentOS $var\n");
 		} else {
 			$distname = 'Redhat';
 			$distver = 'Unknown';