LibVlcUtil: fix library path search

After android-21, libs are not necessarily in applicationInfo.dataDir + "/lib"
folder, so use applicationInfo.nativeLibraryDir (added after Gingerbread).

Also fix system library path search by using
System.getProperty("java.library.path") that return "/vendor/lib:/system/lib"
or "/vendor/lib64:/system/lib64".
LibVLC: fix crash when getMachineSpecs() return null

It can happen with libvlcjni.so library is not found.
Detect TSP, and hide tips for non touch devices
build: fix libgnustl link with arm64-v8a ABI