va-android: same as X11, also always create a new VA display on android
va-android: same as X11, also always create a new VA display on android

Previously a VA display will be shared if a native display is shared by multiple threads,
it will casue some thread safety issue in a multi-threaded program.

Remove the global VADisplayContextP pDisplayContexts which is not thread safe

Signed-off-by: Austin Yuan <f447c34e4ebcef84a81b40a8d4dbc448a14e5570@gmail.com>

Distrotech/libva,Distrotech/libva,pma1/libva,CyanogenMod/android_hardware_intel_libva,halleyzhao/libva-fdo,CyanogenMod/android_hardware_intel_libva,chenxianqin/vaapi-libva,01org/iotg-lin-gfx-libva,android-ia/hardware_intel_libva,gbeauchesne/libva,halleyzhao/libva-fdo,zzhhui/libva,pma1/libva,Distrotech/libva,zzhhui/libva,01org/libva-cros,gbeauchesne/libva,pma1/libva,zzhhui/libva,01org/libva-cros,android-ia/hardware_intel_libva,chenxianqin/vaapi-libva,01org/libva-cros,01org/iotg-lin-gfx-libva,android-ia/hardware_intel_libva,CyanogenMod/android_hardware_intel_libva,halleyzhao/libva-fdo,gbeauchesne/libva,chenxianqin/vaapi-libva,01org/iotg-lin-gfx-libva