Dedup system shared libraries.

These shouldn't differ by target. Right now only mips64 does, and
that's a bug.

Change-Id: Ic941ede85ba1bc07d3316a55639ba71a6afc9630
diff --git a/core/binary.mk b/core/binary.mk
index e18f8c8..96cde0c 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -24,7 +24,7 @@
   endif
 else
   ifeq ($(LOCAL_SYSTEM_SHARED_LIBRARIES),none)
-      my_system_shared_libraries := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_DEFAULT_SYSTEM_SHARED_LIBRARIES)
+      my_system_shared_libraries := libc libm
   else
       my_system_shared_libraries := $(LOCAL_SYSTEM_SHARED_LIBRARIES)
   endif