Add support for ARB_draw_buffers and ARB_occlusion_query. The GLX protocol

Add support for ARB_draw_buffers and ARB_occlusion_query.  The GLX protocol
for these extensions (as well as ARB_vertex_program and ARB_matrix_palette)
was just approved by the ARB on 8-Mar-2005.  Now the only extension missing
for 1.5 support is ARB_vertex_buffer_object.

The opcodes for ARB_matrix_palette were also added to gl_API.xml.  Since
this extension isn't supported by Mesa, no code is generated for it.  Some
tabs were also converted to spaces in the comment for
GetCompressedTexImageARB.