Fix SSSE3 partial_idct_test detection

The test filter is not a prefix matcher. It requires test type to
contain no more than the optimization type. In this example, SSSE3_64
fails to match and the test is not skipped even when SSSE3 is not
available.

Change-Id: Ia74229a167c88da4e6da169012a7a77d438c3f75
Merge "Fix SSSE3 partial_idct_test detection"