Revert "Switch platform-NDK unwinder to LLVM libunwind.a prebuilt"

This reverts commit 85a121323285c9c3b5852c64e9c4ff1550142967.

Reason for revert: b/184095989

Change-Id: I4643a7bb2fea6411d7c673ec4017fdbab6070b9d
diff --git a/core/binary.mk b/core/binary.mk
index 0d7206f..2c20eed 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -266,7 +266,10 @@
       endif
     endif
 
-    my_ndk_stl_static_lib += $(my_libcxx_libdir)/libunwind.a
+    ifneq (,$(filter armeabi armeabi-v7a,$(my_cpu_variant)))
+      my_ndk_stl_static_lib += $(my_libcxx_libdir)/libunwind.a
+    endif
+
     my_ldlibs += -ldl
   else # LOCAL_NDK_STL_VARIANT must be none
     # Do nothing.