build: Use compile_time_request system for init, tasks, and shutdown

Avoid using linker magic to define the init, task, and shutdown
functions.  Instead, use the compile_time_request system.  This
simplifies the build and produces more efficient code.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/endstop.c

@@ -112,7 +112,7 @@ command_end_stop_query(uint32_t *args)
 }
 DECL_COMMAND(command_end_stop_query, "end_stop_query oid=%c");
 
-static void
+void
 end_stop_task(void)
 {
     static uint16_t next;