Use NDK's CMake toolchain for NDK r15+

Use NDK's CMake toolchain for NDK r15+

The ndk-r11.cmake file is pretty complex because neither CMake nor the
NDK provided adequate support. Starting in NDK r15, the NDK provides
an officially supported CMake toolchain file. So dEQP's
ndk-modern.cmake, used for NDK r15 and later, can just delegate to that
for everything that isn't specific to dEQP, instead of duplicating
large parts of it. This will make future NDK versions easier to support.

Components: Framework, AOSP
VK-GL-CTS: 1533

VK-GL-CTS issue: 723
Google bug: 75980403

Change-Id: Icc6ec38601017d2fb6ca40defe2f8e73ba76ca96
(cherry picked from commit 627db59d4b6d74673eda4de10cbbcb934cb99c3f)