cmake: Add support for PNG_ARM_NEON_OPT NDK-r19

cmake: Add support for PNG_ARM_NEON_OPT NDK-r19

On Android, here is clang compiler change for
NDKs after ndk-r17c where the compiler intrinsics
for libpng are not part of the compiler for the
armeabi-v7a targets.

Add the supported png functions for these compiler
intrinsics, explicitly for 32-bit ARM builds.

Affects:
    dEQP-VK.*

Components: Vulkan, Framework
VK-GL-CTS issue: 1638

Change-Id: Ib832f983294f5dd747720ed4a79a21e29a06f776
(cherry picked from commit 99a88af740c425bf250ce9cb2143aa6be3a778f2)