core: remove value for first #define in headers, add "PLUGIN" in plugin headers

src/plugins/script/script.h

@@ -17,8 +17,8 @@
  * along with WeeChat.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef WEECHAT_SCRIPT_H
-#define WEECHAT_SCRIPT_H 1
+#ifndef WEECHAT_PLUGIN_SCRIPT_H
+#define WEECHAT_PLUGIN_SCRIPT_H
 
 #define weechat_plugin weechat_script_plugin
 #define SCRIPT_PLUGIN_NAME "script"
@@ -38,4 +38,4 @@ extern char *script_build_download_url (const char *url);
 extern void script_get_loaded_plugins ();
 extern void script_get_scripts ();
 
-#endif /* WEECHAT_SCRIPT_H */
+#endif /* WEECHAT_PLUGIN_SCRIPT_H */