Fix small tests up to 4 threads.
Fix small tests up to 4 threads.

google/gemmlowp,google/gemmlowp,google/gemmlowp,google/gemmlowp,petewarden/gemmlowp,petewarden/gemmlowp,maciekcc/gemmlowp,petewarden/gemmlowp,maciekcc/gemmlowp,petewarden/gemmlowp,maciekcc/gemmlowp