Android armeabi-v7a build fails with NDK r21

[theeasiestway]

Hello, i can't build openh264 on Windows with ndk version r21 using MSYS2 shell. I get the following repeating errors in log:

F:/Android/Sdk/ndk/21.0.6113669/build/core/add-application.mk:178: *** Android NDK: APP_STL stlport_shared is no longer supported. Please switch to either c++_static or c++_shared. See https://developer.android.com/ndk/guides/cpp-support.html for more information

I use the following command for build:

make OS=android NDKROOT=F:/Android/Sdk/ndk/21.0.6113669 TARGET=android-18 ARCH=arm NDKLEVEL=18 NDK_TOOLCHAIN_VERSION=clang HOST_OS=windows

I scanned "platform-android.mk" file with "$(info)" command and noticed that the "TOOLCHAINPREFIX" and "TOOLCHAIN_NAME" variables are empty and i think perhaps because of this i get the errors above if it so how can i solve it?

[GuangweiWang]

please pick up the latest version to see this issue exists or not