Various changes.

* Makefile: svmodule.c.proto and svgen.py are gone, svmodule.c came in
	their stead.  Also, pass -DUSE_DL flag to thread.c and give
	the user a possibility to add the -DDEBUG to just thread.c.
* ceval.c: init_save_thread() can be called more than once now.
* svgen.py, svmodule.c.proto, svmodule.c: Removed prototype file and
	replaced it by the generated file.
* thread.c: Added some more checks; added call to DL library when it
	is also used to tell it where the shared arena is so that DL
	can use some other area.
* threadmodule.c: Call init_save_thread from another place.  Also,
	added new function getlocklock() which does to lock objects
	what getfilefile does to file objects.

Python/ceval.c

@@ -98,7 +98,7 @@ void
 init_save_thread()
 {
 	if (interpreter_lock)
-		fatal("2nd call to init_save_thread");
+		return;
 	interpreter_lock = allocate_lock();
 	acquire_lock(interpreter_lock, 1);
 }