Fix build.

This project is still using stlport (without telling the build system
about it), which was causing (broken) stlport headers to override
libc++ headers, leading to a broken copy of std::enable_if, which in
turn caused <atomic> to fail to compile. Since this project has
prebuilts that will need to be updated before this project can
actually move away from stlport, tell the build system that it is
still using stlport for now.

Bug: 18433002
Change-Id: I38b356428977ed2184eb28a07bd5e7424a4ace8d
(cherry picked from commit de4bc34719)

libwvdrmengine/cdm/Android.mk

@@ -5,8 +5,6 @@ LOCAL_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 
 LOCAL_C_INCLUDES := \
-    bionic \
-    external/stlport/stlport \
     vendor/widevine/libwvdrmengine/cdm/core/include \
     vendor/widevine/libwvdrmengine/cdm/include \
     vendor/widevine/libwvdrmengine/oemcrypto/include \
@@ -38,7 +36,7 @@ LOCAL_SRC_FILES := \
 
 LOCAL_MODULE := libcdm
 LOCAL_MODULE_TAGS := optional
-
 LOCAL_MODULE_TARGET_ARCH := arm mips x86
+LOCAL_CXX_STL := stlport
 
 include $(BUILD_STATIC_LIBRARY)