r269670 - [OpenCL] Add supported OpenCL extensions to target info.

[Jeroen Ketema via cfe-commits]

Hi Sam,

> This commit does not change the initial state of the extensions. An extension is supported is not the same as enabled. At the beginning all extensions are disabled.

I do not see this reflected in the code at all. Could you please:

a. Point me to the location where this distinction is made.

b. Convince me that I cannot enable an extension for a target if that target does not support the extension?

Jeroen