This update fixes the problem with GLX failing to find a valid configuration on Linux...

This update fixes the problem with GLX failing to find a valid configuration on Linux laptops (Issue 513).

The base issue here was that the default GLX implementation on some Linux laptops lies about its version numbering. Code in SkNativeGLContext_unix.cpp was checking the version number to avoid using FBConfigs in versions prior to 1.3 and thus incorrectly stopped processing.

To resolve this a separate configuration path has been added that uses the pre-1.3 method (i.e., XGetVisualInfo and glXGetConfig). The run-time version check has also been removed and a #define has been added to toggle between the two implementations. This allows the FBConfig method to be used with the wayward GLX implementation while the legacy method can be used with older implementations.

Please see http://codereview.appspot.com/5823049/ for more information.

git-svn-id: http://skia.googlecode.com/svn/trunk@3384 2bbb7eff-a529-9590-31e7-b0007b416f81