Add arch_breakpoint_destroy as a counterpart to arch_breakpoint_init

- even though we don't destroy breakpoints at all right now
diff --git a/common.h b/common.h
index c8e5e5d..4990920 100644
--- a/common.h
+++ b/common.h
@@ -233,6 +233,10 @@
 				       const char *n, GElf_Rela *r, size_t i,
 				       struct library_symbol **ret);
 
+int arch_breakpoint_init(struct Process *proc, struct breakpoint *sbp);
+void arch_breakpoint_destroy(struct breakpoint *sbp);
+
+
 extern struct ltelf main_lte;
 
 #endif