Remove SK_SUPPORT_LEGACY_PUBLICEFFECTCONSTRUCTORS flag.

Neither Chrome nor Android uses this flag anymore.
Make sure all constructors touched that only have one parameter are marked as 'explicit'.

BUG=2187
R=scroggo@google.com, reed@google.com

Author: dominikg@chromium.org

Review URL: https://codereview.chromium.org/282203004

git-svn-id: http://skia.googlecode.com/svn/trunk@14749 2bbb7eff-a529-9590-31e7-b0007b416f81
26 files changed