Audio VTS: improve audio policy validation error messages

If multiple config are found, each will be validated before failing the
test.
Also add a missing new line before dumping libxml2 errors.

Test: run the following script to check for regressions and test that
      invalid config make the test fail.

    runTest() {(
      set -xu
      local readonly MODULE=$1
      local readonly TEST=$2
      local readonly XML=$3
      runVTS() { vts-tradefed run commandAndExit vts \
            --skip-all-system-status-check --primary-abi-only \
            --skip-preconditions --module $MODULE -t $TEST |
                 awk '/FAILED: 0/{e=1} {print} END {exit !e}'; }

      local FAIL=0 # used instead of return if clean up is needed

      echo "# Test valid config"
      runVTS || return 1

      echo "# Test multiple invalid match"
      adb shell touch /system/etc/$XML
      runVTS && FAIL=2
      adb shell rm /system/etc/$XML

      echo "# Test multiple valid match (not supported if xinclude)"
      if !adb shell grep -q xi:include /vendor/etc/$XML; then
        adb shell cp /{vendor,system}/etc/$XML
        runVTS || FAIL=3
        adb shell rm /system/etc/$XML
      fi

      echo "# Test invalid config"
      adb shell sed -i "'2i<fuu/>'" /vendor/etc/$XML
      runVTS && FAIL=4
      adb shell sed -i 2d /vendor/etc/$XML

      echo "#Test no config"
      adb shell mv /vendor/etc/$XML{,.hide}
      runVTS && FAIL=5
      adb shell mv /vendor/etc/$XML{.hide,}

      echo "# Test that the test did not break the config"
      runVTS || FAIL=6

      return $FAIL
    )}
    runTest VtsHalAudioV2_0Target CheckConfig.audioPolicyConfigurationValidation audio_policy_configuration.xml &&
    runTest VtsHalAudioEffectV2_0Target CheckConfig.audioEffectsConfigurationValidation audio_effects.xml &&
    echo TEST PASSED

Bug: 64881365
Change-Id: If0443f85e0d687eed04819337519e4d9f09f5ca9
Signed-off-by: Kevin Rocard <krocard@google.com>