IPCCompiler: Use string hashes for IPC endpoint magic

This patch removes the IPC endpoint numbers that needed to be specified
in the IPC files.  Since the string hash is a (hopefully) collision free
number that depends on the name of the endpoint, we now use that
instead. :^)

Userland/Services/WindowServer/WindowClient.ipc

@@ -1,4 +1,4 @@
-endpoint WindowClient = 4
+endpoint WindowClient
 {
     Paint(i32 window_id, Gfx::IntSize window_size, Vector<Gfx::IntRect> rects) =|
     MouseMove(i32 window_id, Gfx::IntPoint mouse_position, u32 button, u32 buttons, u32 modifiers, i32 wheel_delta, bool is_drag, Vector<String> mime_types) =|

Userland/Services/WindowServer/WindowManagerClient.ipc

@@ -1,4 +1,4 @@
-endpoint WindowManagerClient = 1872
+endpoint WindowManagerClient
 {
     WindowRemoved(i32 wm_id, i32 client_id, i32 window_id) =|
     WindowStateChanged(i32 wm_id, i32 client_id, i32 window_id, i32 parent_client_id, i32 parent_window_id, bool is_active, bool is_minimized, bool is_modal, bool is_frameless, i32 window_type, [UTF8] String title, Gfx::IntRect rect, i32 progress) =|

Userland/Services/WindowServer/WindowManagerServer.ipc

@@ -1,4 +1,4 @@
-endpoint WindowManagerServer = 1871
+endpoint WindowManagerServer
 {
     SetEventMask(u32 event_mask) => ()
     SetManagerWindow(i32 window_id) => ()

Userland/Services/WindowServer/WindowServer.ipc

@@ -1,4 +1,4 @@
-endpoint WindowServer = 2
+endpoint WindowServer
 {
     Greet() => (Gfx::IntRect screen_rect, Core::AnonymousBuffer theme_buffer)