Add prioritydumper_test to device_tests

BUG: 27429130

Test: make -j56 device_tests
Test: mmm -j56 frameworks/native/services/utils && \
      adb sync data && adb shell /data/nativetest/prioritydumper_test/prioritydumper_test && \
      adb shell /data/nativetest64/prioritydumper_test/prioritydumper_test && \
      printf "\n\n#### ALL TESTS PASSED ####\n"

Change-Id: I2f00a684da162c1ffd96d5fc478463f7f0cd7b61