Update {virtual,override} to follow C++11 style in src/fonts.

Update {virtual,override} to follow C++11 style in src/fonts.

The Google style guide states that only one of {virtual,override,final}
should be used for each declaration, since override implies virtual and
final implies both virtual and override.

The entries were found using the following command line:

$ find src/fonts -iname "*.h" -o -iname "*.cpp" | xargs pcregrep -M
"[^\n/]+virtual\ [^;{]+\ [a-zA-Z0-9_]+\([^;{]+\ override[ \n]*[;{]"

The regex was a courtesy of nick@chromium.org

BUG=None
R=mtklein@google.com

Committed: https://skia.googlesource.com/skia/+/37a92b44373a6ace53d7f446206e9dc544fff288

[mtklein, 2015-04-24 21:19:57]

The CQ bit was checked by mtklein@google.com

[mtklein, 2015-04-24 21:19:58]

lgtm

[commit-bot: I haz the power, 2015-04-24 21:20:10]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1101343002/1

[commit-bot: I haz the power, 2015-04-24 21:25:39]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/37a92b44373a6ace53d7f446206e9dc544fff288