Enable unit test for partial 16x16 inverse 2D-DCT

This commit enables unit test for SSSE3 16x16 inverse 2D-DCT with
10 non-zero coefficients. It includes a new test condition to
cover the potential overflow issue due to extremely coarse quantization.

Change-Id: I945e16f05dfbe19500f0da5f15990feba8e26d99
1 file changed