Parameterize SignatureTest with expected api files

Replaces a hard coded api file name with a list of api file names
provided as a comma separated instrumentation-arg in the AndroidTest.xml
file. This will allow the same code to be used to test multiple
different API definitions simply by changing the AndroidTest.xml.

Cleaned up some warnings and poorly structured code (e.g. empty while
loops).

Tested using:
    m -j32 CtsApiSignatureTestCases && \
        cts-tradefed run cts -a arm64-v8a -m CtsApiSignatureTestCases

Bug: 35192974
Bug: 30188076
Test: see above
Change-Id: Ie756b094db2ee232f58bce6fa85f306c9d4df7d6
3 files changed