enable gnu extensions to get strcasestr from string.h

content/handlers/html/html_css.c

@@ -21,6 +21,8 @@
  * Processing for html content css operations.
  */
 
+#define _GNU_SOURCE /* strcasestr needs this for string.h */
+
 #include <assert.h>
 #include <ctype.h>
 #include <stdint.h>

desktop/treeview.c

@@ -22,6 +22,8 @@
  * Treeview handling implementation.
  */
 
+#define _GNU_SOURCE /* strcasestr needs this for string.h */
+
 #include <string.h>
 
 #include "utils/utils.h"