Fix libthread_db linkage

libthread_db depends on libc but since unresolved symbols were allowed
in the makefile this problem was never realized until gdbserver tried
to link with it, failing in the runtime.

Change-Id: If2ee319a2503c81abf3010829444f920c7c0c227
diff --git a/libthread_db/Android.mk b/libthread_db/Android.mk
index 3091bbc..922b9cf 100644
--- a/libthread_db/Android.mk
+++ b/libthread_db/Android.mk
@@ -21,7 +21,7 @@
 
 LOCAL_WHOLE_STATIC_LIBRARIES := libthread_db
 LOCAL_MODULE:=libthread_db
-LOCAL_SHARED_LIBRARIES := libdl
+LOCAL_SHARED_LIBRARIES := libdl libc
 
 # NOTE: Using --no-undefined results in a missing symbol that is defined inside
 # gdbserver and is resolved at runtime. Since there is no library containing