Geforce 8 and Geforce 9 cards support 256 env and 1024 native
constants. 1024 is the hardware limit we want to use if we overwrite
the GLSL reported value with the ARB value on Mac OS (because Mac OS
reports more constants than supported by HW on some cards).

Some version of Mesa will claim the window system provided framebuffer is
incomplete when using indirect rendering, although the framebuffer objects
spec says this can never happen. Printing an ERR instead of crashing should
make it clearer that this isn't a wined3d problem.

Found by valgrind.

We use it to do a linear search of a binary tree, which is overkill.
Replace it with a simple binary search.