PyAPI: free internal Python data using sys.exit(..)

Previously BPY_python_end wasn't called when scripts called sys.exit()
because BPY_python_end exited the Python interpreter.

Change this behavior to call BPY_python_end without exiting the Python
interpreter while freeing Blender/Python data.

While leaks in the context of sys.exit aren't especially important
it's generally preferable for sys.exit() to match Blender's code-paths
for exiting to avoid unexpected behavior.

source/blender/python/BPY_extern_python.h

@@ -23,7 +23,7 @@ extern "C" {
 
 /** Call #BPY_context_set first. */
 void BPY_python_start(struct bContext *C, int argc, const char **argv);
-void BPY_python_end(void);
+void BPY_python_end(bool do_python_exit);
 void BPY_python_reset(struct bContext *C);
 void BPY_python_use_system_env(void);
 void BPY_python_backtrace(FILE *fp);