Add libunwindstack to dependencies.

Test: Builds.
Change-Id: Icb68b8532458a0e761e82bbc2f32dbc835c4fd7b
diff --git a/Android.bp b/Android.bp
index 569179d..5e3a8d8 100644
--- a/Android.bp
+++ b/Android.bp
@@ -12,6 +12,7 @@
     "libcutils",
     "libunwindbacktrace",
     "libunwind",
+    "libunwindstack",
     "libutils",
     "libbase",
     "liblz4",