libsysprof-capture: Move autocleanup definitions to libsysprof

In preparation for dropping the GLib dependency from libsysprof-capture,
move the autocleanup definitions up to libsysprof. Add a new header for
them.

This is slightly awkward in the tools, which depend on
libsysprof-capture but not libsysprof. Rather than make them depend on
libsysprof (which might be disabled at configure time), include the
`sysprof-capture-autocleanups.h` file between source directories.
`SYSPROF_COMPILATION` needs to be defined for this to work.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

Helps: #40

src/tools/list-threads.c

@@ -24,6 +24,8 @@
 #include <sysprof-capture.h>
 #include <unistd.h>
 
+#include "../libsysprof/sysprof-capture-autocleanups.h"
+
 static gboolean
 foreach_cb (const SysprofCaptureFrame *frame,
             gpointer                   user_data)