xmllint: Fix --pedantic option

Regressed in 74c84a8c.
diff --git a/xmllint.c b/xmllint.c
index 5c26c3f..82a8786 100644
--- a/xmllint.c
+++ b/xmllint.c
@@ -3350,7 +3350,7 @@
 	else if ((!strcmp(argv[i], "-pedantic")) ||
 	         (!strcmp(argv[i], "--pedantic"))) {
 	    options |= XML_PARSE_PEDANTIC;
-            options &= XML_PARSE_NOWARNING;
+            options &= ~XML_PARSE_NOWARNING;
         }
 #ifdef LIBXML_DEBUG_ENABLED
 	else if ((!strcmp(argv[i], "-debugent")) ||