CaWE release build cannot load RendererOpenGL12

[Carsten]

CaWE release build shows a message box with text:

Renderer Libs/build/linux2/g++/release/MaterialSystem/libRendererOpenGL12.so says that it's not supported.

(This may be caused by your desktop being set to 16 BPP (or less). Please set your desktop bit-depth to 32 BPP (True Color), and try again.)

then aborts at the console:

carsten@thubi-ubuntu:~/Cafu$ ./build/linux2/g++/release/CaWE/CaWE 
pure virtual method called
terminate called without an active exception
Aborted

The same is not true for the debug build.

[Carsten]

This patch fixes the issue, but should be tested also under Windows before being applied.

[Carsten]

Fixed by r41.