This workaround is temporary, until filter-intra can work with rectangular
blocks.

Tested OK:
make clean; ../../configure --disable-install-docs --enable-unit-tests
--enable-debug --enable-aom-highbitdepth --enable-experimental
--enable-adapt-scan --enable-dual-filter --enable-ext-inter
--enable-ext-intra --enable-ext-refs --enable-ext-tx
--enable-filter-intra --enable-loop-restoration --enable-rect-tx
--enable-compound-segment --enable-interintra --enable-wedge
make -j
./test_libaom

Change-Id: I4554d1f25de9448b22465e93a7616df0c206e298