Call all ewmh_update_* functions together when necessary

The testcase is changed because it was actually incorrect. Easy to
verify because:
> _NET_CURRENT_DESKTOP
> …
> The index of the current desktop. This is always an integer between 0
> and _NET_NUMBER_OF_DESKTOPS - 1.

Fixes #3696.
Also updates the viewports.

Finally, fixes an issue with _NET_CURRENT_DESKTOP not being updated
after a workspace rename. Example:
- workspaces 1, 2, 3
- rename workspace 1 to 5
- All workspaces changed their index but _NET_CURRENT_DESKTOP was not
updated

src/ewmh.c

@@ -39,7 +39,7 @@ void ewmh_update_current_desktop(void) {
  * Updates _NET_NUMBER_OF_DESKTOPS which we interpret as the number of
  * noninternal workspaces.
  */
-void ewmh_update_number_of_desktops(void) {
+static void ewmh_update_number_of_desktops(void) {
     Con *output, *ws;
     static uint32_t old_idx = 0;
     uint32_t idx = 0;
@@ -61,7 +61,7 @@ void ewmh_update_number_of_desktops(void) {
  * Updates _NET_DESKTOP_NAMES: "The names of all virtual desktops. This is a
  * list of NULL-terminated strings in UTF-8 encoding"
  */
-void ewmh_update_desktop_names(void) {
+static void ewmh_update_desktop_names(void) {
     Con *output, *ws;
     int msg_length = 0;
 
@@ -88,7 +88,7 @@ void ewmh_update_desktop_names(void) {
  * Updates _NET_DESKTOP_VIEWPORT, which is an array of pairs of cardinals that
  * define the top left corner of each desktop's viewport.
  */
-void ewmh_update_desktop_viewport(void) {
+static void ewmh_update_desktop_viewport(void) {
     Con *output, *ws;
     int num_desktops = 0;
     /* count number of desktops */
@@ -109,6 +109,18 @@ void ewmh_update_desktop_viewport(void) {
                         A__NET_DESKTOP_VIEWPORT, XCB_ATOM_CARDINAL, 32, current_position, &viewports);
 }
 
+/*
+ * Updates all the EWMH desktop properties.
+ *
+ */
+void ewmh_update_desktop_properties(void) {
+    ewmh_update_number_of_desktops();
+    ewmh_update_desktop_viewport();
+    ewmh_update_current_desktop();
+    ewmh_update_desktop_names();
+    ewmh_update_wm_desktop();
+}
+
 static void ewmh_update_wm_desktop_recursively(Con *con, const uint32_t desktop) {
     Con *child;