Android ndk-gdb updates for API21

# Get the app_server binary from the device
APP_PROCESS=$APP_OUT/app_process
if [ "$API_LEVEL" -lt "21" ] ; then
    run adb_cmd pull /system/bin/app_process `native_path $APP_PROCESS`
    log "Pulled app_process from device/emulator to $APP_PROCESS"
else
    run adb_cmd pull /system/bin/app_process32 `native_path $APP_PROCESS`
    log "Pulled app_process32 from device/emulator to $APP_PROCESS"
fi

OR:

# Get the app_server binary from the device
APP_PROCESS=$APP_OUT/app_process
APP_PROCESS_DEVICE=app_process32
if [ "$API_LEVEL" -lt "21" ] ; then
    APP_PROCESS_DEVICE=app_process
fi
run adb_cmd pull /system/bin/$APP_PROCESS_DEVICE `native_path $APP_PROCESS`
log "Pulled $APP_PROCESS_DEVICE from device/emulator to $APP_PROCESS"