Mark the modules as VNDK-SP in Android.bp

As a VNDK-SP module, Android.bp must have 'vndk' tag as well as
'vendor_available: true'.

The 'vndk' tag for VNDK-SP formated as follows:
vndk: {
    enabled: true,
    support_system_process: true,
},

VNDK-SP modules will be installed both in system/lib(64) as normal
and in system/lib(64)/vndk-sp as a vendor variant.

Bug: 63866913
Test: build and boot with BOARD_VNDK_VERSION=current
Change-Id: I51fe0859f63ad58b7b91909e7d7d4206443228cd