[C++] Clean up architecture specific compiler flags

[asfimport]

I noticed that -maltivec is being passed to the compiler on Linux, with an x86_64 processor. That seemed odd to me. It prompted me to look more generally at our compiler flags related to hardware optimizations. We have the ability to pass -msse3, but there is a ARROW_USE_SSE which is only used as a define in some headers. There is ARROW_ALTIVEC, but no option to pass -march. Nothing related to AVX/AVX2/AVX512. I think this could do for an overhaul

Reporter: Wes McKinney / @wesm

_{Note: This issue was originally created as ARROW-2186. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Is this fixed now maybe?

[asfimport]

Antoine Pitrou / @pitrou:
@wesm I think so.