Faster set/setr

[p0nce]

Very common pattern.

Fastest on LDC: (only make a difference in -O0)

    {
        __m128 r = void;
        r.ptr[0] = e3; // .ptr doesn't matter here
        r.ptr[1] = e2;
        r.ptr[2] = e1;
        r.ptr[3] = e0;
        return r;
    }

This saves instructions in debug mode. .ptr doesn't change anything in both LDC and GDC, on all optimization levels.

The fun thing is that on GDC the fastest is also the same, and wins a bit in all optimization levels with the = void;

• [x] Remove useless loadUnaligned in favor of above form => related to #70
• [x] Find all __m128 r; patterns, mark with PERF tag if common.
• [x] _mm_setr_ps

[p0nce]

Marked many places with PERF tag, where a =void; could be beneficial in -O0