wined3d base GLX requirement

[Ivan Gyurdiev]

The current base GLX requirement for wined3d seems to be v1.3.
It won't compile otherwise... I wrote a patch for pbuffers, which adds 
proper extension support for SGIX_PBUFFER and SGIX_FBCONFIG, but:

- even with the patch there's additional offenders in directx.c that 
prevent a compile with glx < 1.3 [ more FBCONFIG dependencies ]
- there's comments in the source saying ATI supports pbuffers, but only 
advertises GLX_VERSION_1_3, without the appropriate extensions.

So - should GLX 1.3 be considered a base requirement for wined3d, or 
should I send patches to clean up pbuffer dependencies?