Fix file_contexts CTS tests

Bug: 38502071
Test: cts-tradefed run singleCommand cts --skip-device-info \
    --skip-preconditions --skip-connectivity-check --abi arm64-v8a \
    --module CtsSecurityHostTestCases \
    -t android.security.cts.SELinuxHostTest#testAospFileContexts
Test: cts-tradefed run singleCommand cts --skip-device-info \
    --skip-preconditions --skip-connectivity-check --abi arm64-v8a \
    --module CtsSecurityHostTestCases \
    -t android.security.cts.SELinuxHostTest#testValidFileContexts

Change-Id: I1b18d0ddd0840329b8830822f8abbb1b207d7d72
1 file changed