Updates the convolve test to verify that all filters match the
reference implementation. This verifies commit 30f866f4, which
fixed some problems with the SSE3 version of the filters for
the vp9_sub_pel_filters_8s and vp9_sub_pel_filters_8lp banks
due to overflow and order of operations.

Change-Id: I6b5fe1a41bc20062e2e64633b1355ae58c9c592c