Guard against most unintentionally ephemeral SkAutoFoo instantiations.

Guard against most unintentionally ephemeral SkAutoFoo instantiations.

I think I applied the trick everywhere possible.  Limitations:
    - can't be used with templated classes
    - all constructors and destructors must be defined inline

A couple of the SkAutoFoo were unused in Skia, Chromium, and Android, so I
deleted them.  This change caught the same bugs Cary found in SkPath, plus one
more in SampleApp.

BUG=
R=reed@google.com, caryclark@google.com

Author: mtklein@google.com

Review URL: https://codereview.chromium.org/72603005

git-svn-id: http://skia.googlecode.com/svn/trunk@12301 2bbb7eff-a529-9590-31e7-b0007b416f81