unwind: delete mmap cache in free_libunwind_ui

free_libunwind_ui is expected to release all unwind related resources
attached to tcp.

* strace.c (droptcb): Move delete_mmap_cache call ...
* unwind.c (free_libunwind_ui): ... to here.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
diff --git a/unwind.c b/unwind.c
index 7c179bf..fc97ea2 100644
--- a/unwind.c
+++ b/unwind.c
@@ -69,6 +69,7 @@
 void
 free_libunwind_ui(struct tcb *tcp)
 {
+	delete_mmap_cache(tcp);
 	_UPT_destroy(tcp->libunwind_ui);
 	tcp->libunwind_ui = NULL;
 }