[X86] SSE4_A should only imply SSE3 not SSSE3 in the frontend. SSE4_1 and SSE4_2 due imply SSSE3. So I guess I got confused when switching the code to being table based in D83273. Fixes PR47464 This should fix builds with -march=amdfam10 emitting SSSE3 instructions such as pshufb, which lead to programs crashing with SIGILL on such processors. Reported by: avg MFC after: 6 weeks X-MFC-With: r364284