winex11.drv/opengl.c: add error handling to pglXMakeCurrent() call

[Joshua Beck]

This patch should make it easier for those with driver problems to find 
the problem when running Wine.
--Josh
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: 0001-modified-dlls-winex11.drv-opengl.c.txt
URL: <http://www.winehq.org/pipermail/wine-patches/attachments/20110323/b3aa87e9/attachment.txt>