SkCpu w/o static initializer

I think I cracked it.

Though, this may not technically be legal C++...
I've only got one definition of SkCpu::gCachedFeatures,
but two different declarations: non-const in SkCpu.cpp, const elsewhere.

Is this...
   - legal C++?
   - not C++ but probably works as I think?
   - not C++ and will probably blow up?
   - who knows, let's see?

I have tested that the features are cached properly, read properly, and that the generated code treats SkCpu::gCachedFeatures as a global constant outside SkCpu.cpp.  So it all observably works optimally.

Expanding testing to more bots.
TBR=reed@google.com

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1905683003

Review URL: https://codereview.chromium.org/1905683003
3 files changed