Dynamically load dwmapi.dll

Dynamically load/free dwmapi.dll so that libEGL.dll will load on systems without desktop compositing (e.g. Windows XP).

[apatrick1, 2013-03-19 21:57:25]

dwmapi.dll is supposed to be delay loaded. Build options include
/DELAYLOAD:"dwmapi.dll". Is this not working?

That said, I think the DWM code is not needed anymore. Easiest thing is just
delete it. I'll see if that works okay...

[baustin, 2013-03-19 22:48:18]

On 2013/03/19 21:57:25, apatrick1 wrote:
> dwmapi.dll is supposed to be delay loaded. Build options include
> /DELAYLOAD:"dwmapi.dll". Is this not working?

We're using our own build system for libEGL, and didn't have DELAYLOAD set. 
I'll give DELAYLOAD a try, although probably won't be able to test on XP for a
while.

> 
> That said, I think the DWM code is not needed anymore. Easiest thing is just
> delete it. I'll see if that works okay...

If the DWM code can't be deleted, using /DELAYLOAD for DWM seems a little
fragile.  If someone adds a call to a DWM function without first checking the OS
version, ANGLE will still compile and run fine on Vista and newer, but will be
broken on XP.

[apatrick1, 2013-03-20 19:09:38]

I'll do this:
https://codereview.appspot.com/7872045/