Fix an unaligned memory allocation in HT 4x4 speed test
Fix an unaligned memory allocation in HT 4x4 speed test

- Allocate 16-byte aligned memory.
- Disable speed test in unit tests.

Change-Id: Ibef734f4b9d39ad50e9b2e8e0a5d74565d57b409

smarter/aom,luctrudeau/aom,mbebenita/aom,smarter/aom,mbebenita/aom,mbebenita/aom,smarter/aom,mbebenita/aom,luctrudeau/aom,GrokImageCompression/aom,luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,mbebenita/aom,luctrudeau/aom,smarter/aom,mbebenita/aom,GrokImageCompression/aom,GrokImageCompression/aom,smarter/aom,smarter/aom,mbebenita/aom,GrokImageCompression/aom,mbebenita/aom,mbebenita/aom,luctrudeau/aom,luctrudeau/aom