Don't manually link stlport.

Change-Id: Ib9efbf25a988297b20103a796fd279d2a66c894c
diff --git a/Android.mk b/Android.mk
index 0307ce3..6543453 100644
--- a/Android.mk
+++ b/Android.mk
@@ -38,19 +38,20 @@
 # Stlport version
 # =======================================================
 include $(CLEAR_VARS)
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_MODULE := libregex-re2
 LOCAL_MODULE_TAGS := optional
 LOCAL_CPP_EXTENSION := .cc
-LOCAL_C_INCLUDES += $(LOCAL_PATH)/re2 \
-		    external/stlport
+LOCAL_C_INCLUDES += $(LOCAL_PATH)/re2
 LOCAL_SRC_FILES := $(regexp_re2_files)
-include external/stlport/libstlport.mk
+LOCAL_CXX_STL := stlport
 include $(BUILD_STATIC_LIBRARY)
 
 # Gnustl+rtti version
 # =======================================================
 
 include $(CLEAR_VARS)
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_MODULE := libregex-re2-gnustl-rtti
 LOCAL_MODULE_TAGS := optional
 LOCAL_CPP_EXTENSION := .cc
@@ -59,5 +60,4 @@
 LOCAL_CFLAGS += -frtti
 LOCAL_NDK_STL_VARIANT := gnustl_static
 LOCAL_SDK_VERSION := 14
-
 include $(BUILD_STATIC_LIBRARY)