Don't re-export libunwind_llvm.

Change-Id: Ic16be4ada4cff374209d5eea89a7f81ed2fff398
diff --git a/libc/Android.mk b/libc/Android.mk
index ca20d3d..c75b825 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -1445,6 +1445,7 @@
 # Only need this for arm since libc++ uses its own unwind code that
 # doesn't mix with the other default unwind code.
 LOCAL_STATIC_LIBRARIES_arm := libunwind_llvm
+LOCAL_LDFLAGS_arm := -Wl,--exclude-libs,libunwind_llvm.a
 LOCAL_STATIC_LIBRARIES += libc++abi
 LOCAL_ALLOW_UNDEFINED_SYMBOLS := true