WineD3D: Only perform sRGB write correction on formats that advertise it

[Stefan Dösinger]

This patch is independent of my test patches.

I have a test in my git tree that confirm this patch, I'll send it when the 
testsuite passes again on at least one of my windows systems.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0003-WineD3D-Only-perform-sRGB-write-correction-on-format.patch
Type: text/x-patch
Size: 3532 bytes
Desc: not available
URL: <http://www.winehq.org/pipermail/wine-patches/attachments/20100706/5d8719ba/attachment.bin>