Go back to storeAligned / LoadAligned for SkPMFloat <->Sk4f.

This seems to fix the miscompilation bug on ARM64 / Release / GCC 4.9.

We switched this over originally for perf issues with NEON, but I can't see any now.  Will keep an eye out.

BUG=skia:3570

Review URL: https://codereview.chromium.org/1026403002
2 files changed