Fix rules for libstlport

Change-Id: I571e906173c9e70de97e3cfefd10da5137dba4d4
diff --git a/Android.mk b/Android.mk
index 47c4aa1..5ee7bf9 100644
--- a/Android.mk
+++ b/Android.mk
@@ -109,7 +109,7 @@
 LOCAL_SHARED_LIBRARIES += libz libc libcutils libstdc++ libtar libblkid libminuitwrp libminadbd libmtdutils libminzip libaosprecovery
 LOCAL_SHARED_LIBRARIES += libcrecovery
 
-ifneq ($(wildcard external/stlport/Android.mk),)
+ifeq (,$(filter $(PLATFORM_SDK_VERSION), 23))
     LOCAL_SHARED_LIBRARIES += libstlport
 else
     LOCAL_SHARED_LIBRARIES += libc++
diff --git a/mtp/Android.mk b/mtp/Android.mk
index 2040425..38d31ae 100755
--- a/mtp/Android.mk
+++ b/mtp/Android.mk
@@ -31,7 +31,7 @@
     node.cpp
 LOCAL_SHARED_LIBRARIES += libz libc libusbhost libstdc++ libdl libcutils libutils libaosprecovery
 
-ifneq ($(wildcard external/stlport/Android.mk),)
+ifeq (,$(filter $(PLATFORM_SDK_VERSION), 23))
     LOCAL_SHARED_LIBRARIES += libstlport
 else
     LOCAL_SHARED_LIBRARIES += libc++