meson: Fix define for USE_SSE41

Before we were adding -DHAVE_SSE41 which isn't what the code is
looking for, so some uses of the sse4.1 code were always being
skipped.

v2: Don't add any compile check for the quite old -msse4.1 option (Dylan)

Fixes: 84486f6462 ("meson: Enable SSE4.1 optimizations")
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
1 file changed