Use ErrorF for an error message after an xcalloc failure, and return instead of falling through to GlxSetVisualConfigs, or abort()ing at the test branch.
(cherry picked from commit 1056700971fd5c034396ed6dbea15e092f0c6332)
Commit the darwin.c changes I missed in the last commit, for calling
setVisualConfigs().
(cherry picked from commit eb3c014e1710bf0b93bda10ddb9b795cd150d02d)
Add a setVisualConfigs that is called before the fbScreenInit, to setup the __GLXvisualConfigs.
(cherry picked from commit fc86f9e4482043eca76d9d7a96e166be1aabf674)