Revert of Clean up SSSE3 and SSE4 stubs. (patchset #1 id:1 of https://codereview...

Revert of Clean up SSSE3 and SSE4 stubs. (patchset #1 id:1 of https://codereview.chromium.org/1810183003/ )

Reason for revert:
I've just had a better idea about how to fix this.  Let's revert while I work on it.

Original issue's description:
> Clean up SSSE3 and SSE4 stubs.
>
> We added these stubs to work around OpenBSD's old compiler, which had
> support for SSE2 but not SSSE3 or SSE4.
>
> We now already have other unstubbed files that require SSSE3 and SSE4 compiler
> support.  All the compilers we support have SSSE3 and SSE4 support, and all the
> way up to at least AVX2.
>
> (Requiring C++11 has had some nice ripple effects...)
>
>
> And, <immintrin.h> is already auto-included for these files, so no need for smmintrin or tmmintrin.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1810183003
> CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
>
> Committed: https://skia.googlesource.com/skia/+/2b1b40e11afc41452b4d2f74cdebb1b6e6f7cc96

TBR=djsollen@google.com,mtklein@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=skia:

Review URL: https://codereview.chromium.org/1819223003