Cryptic error message from 0xbench test if 0xbench not found

[Frans Gifford]

0xbench test install will fail with a cryptic error if 0xbench is not already installed on the device under test (here-ish https://bazaar.launchpad.net/~linaro-validation/lava-android-test/trunk/view/head:/lava_android_test/test_definitions/android-0xbenchmark/android_0xbenchmark_modify_path.py#L41).

Since the test goes to the trouble of checking if 0xbench is installed/accessible, it should give a more obvious error message if it can't find it. In fact, lava-android-test *run* 0xbench does give an obvious error if 0xbench is missing, it's just *install* that doesn't.

AFAIK, Linaro builds *always* include 0xbench, but AOSP builds *never* contain it, so this only really affects non-Linaro builds/hardware.

Expected output: (this is what lava-android-test run 0xbench reports)
LAVA: (stdout) Error: Activity class {org.zeroxlab.zeroxbenchmark/org.zeroxlab.zeroxbenchmark.Benchmark} does not exist.

Actual output:
$ lava-android-test install 0xbench
LAVA: --Start Operation: Install test (0xbench)
LAVA: Begin to execute command: python /build/lava-android-test-env/lib/python2.7/site-packages/lava_android_test-0.6.dev-py2.7.egg/lava_android_test/test_definitions/android-0xbenchmark/android_0xbenchmark_modify_path.py
LAVA: (stdout) Failed to get group and owner of directory(/data/data): drwxr-x--x app_1 app_1 2012-06-08 13:54 com.android.backupconfirm
LAVA: (stdout) drwxr-x--x app_2 app_2 1970-01-02 07:59 com.android.bluetooth
...

[Yongqin Liu (liuyq0307)]

The 0xbench test integrated into lava-android-test already assumed that the 0xbench application has been integrated into the android image.
If the 0xbench application is not integrated then the 0xbench test should not be included int the tests.
otherwise the test has no meaning.

If we want to test 0xbench on an android that 0xbench application is not installed,
I think we'd better integrate another 0xbench test into lava-android-test that will install 0xbench application and run the test.