libsysprof: use embedded kallsyms when possible

This uses the kallysms that has been embedded in the capture file when
that is possible (such as when proc-source appends it).

src/tests/test-kallsyms.c

@@ -2,6 +2,8 @@
 #include <stdlib.h>
 #include <sysprof.h>
 
+#include "sysprof-kallsyms.h"
+
 int
 main (gint argc,
       gchar *argv[])