Fix scan_build warnings in convolve_test.cc
Fix scan_build warnings in convolve_test.cc

Change-Id: I87e1c3f0492cde805b54b048385ea200652dfccc

ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx,ShiftMediaProject/libvpx,webmproject/libvpx,ShiftMediaProject/libvpx