Add support for multiple render targets in glClear.

TRAC #22659

Signed-off-by: Nicolas Capens
Signed-off-by: Shannon Woods
Author: Jamie Madill

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@2019 736b8ea6-26fd-11df-bfd4-992fa37f6226
6 files changed