libsysprof: add versioning macros

This also moves stackstash.[ch] into a location that can be
embedded by both the libsysprof and libsysprof-ui code. We
pass native pointers to the structure as a gpointer in the
public API to allow for this. The performance of that code is
incredibly sensitive to the interactivity of Sysprof.

src/libsysprof/sp-source-util.c

@@ -18,6 +18,8 @@
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
 
+#include "config.h"
+
 #include <gio/gio.h>
 #include <string.h>