Disable Lanczos and Blur for fglrx

Too many crash reports in the fglrx driver when using ARB shaders.
It's a pity to disable functionality for all fglrx users, but it's
better than crash reports.

Blur effect can still be enabled manually and Lanczos can still be
enabled through the environment variable.

REVIEW: 103556
CCBUG: 270818
CCBUG: 286795