Revert "While we can, restrict SkFixedAlloc/SkFallbackAlloc to POD."

This reverts commit 1ee70359a199f161ce38451989a706d727954cc1.

Reason for revert: breaking my various rolls.

Original change's description:
> While we can, restrict SkFixedAlloc/SkFallbackAlloc to POD.
> 
> This trims the overhead down to a uniform 4 bytes.
> 
> BUG=skia:
> 
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4786
> 
> Change-Id: I92127a0c2d6c23a4a372eca39842e22195d2dc99
> Reviewed-on: https://skia-review.googlesource.com/4786
> Reviewed-by: Herb Derby <herb@google.com>
> Commit-Queue: Mike Klein <mtklein@chromium.org>
> 

TBR=mtklein@chromium.org,herb@google.com,reviews@skia.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: Iae9ef553422352a1abf95b709fccd014d468da86
Reviewed-on: https://skia-review.googlesource.com/4829
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
5 files changed