t/test-deb716628.sh: don't generate a core file if the test fails
test-gh1: new

this adds a test case based on github Issue #1.

the two data files are compressed MTBL files generated with something
like the following python script:

    import mtbl

    w = mtbl.writer('test-gh1-snappy.data', compression=mtbl.COMPRESSION_SNAPPY)
    w['key1'] = '1' * 30000
    w.close()

    w = mtbl.writer('test-gh1-zlib.data', compression=mtbl.COMPRESSION_ZLIB)
    w['key1'] = '1' * 30000
    w.close()