remove #if logic for openocd_sleep_*lude

Adds server_stubs.c to hold these routines, using automake logic to
ensure it gets included under the right conditions.

src/openocd.h

@@ -31,11 +31,6 @@
  */
 int openocd_main(int argc, char *argv[]);
 
-/// used by the server_loop() function in src/server/server.c
-void openocd_sleep_prelude(void);
-/// used by the server_loop() function in src/server/server.c
-void openocd_sleep_postlude(void);
-
 /// provides a hard-coded command environment setup
 extern const char openocd_startup_tcl[];