mesa: increase MAX_DRAW_BUFFERS to 8

Required for GL 3.x

src/mesa/main/config.h

@@ -250,7 +250,7 @@
 
 /** For GL_ARB_draw_buffers */
 /*@{*/
-#define MAX_DRAW_BUFFERS 4
+#define MAX_DRAW_BUFFERS 8
 /*@}*/
 
 

src/mesa/main/context.c

@@ -652,6 +652,9 @@ check_context_limits(GLcontext *ctx)
 
    assert(ctx->Const.MaxDrawBuffers <= MAX_DRAW_BUFFERS);
 
+   /* if this fails, add more enum values to gl_buffer_index */
+   assert(BUFFER_COLOR0 + MAX_DRAW_BUFFERS <= BUFFER_COUNT);
+
    /* XXX probably add more tests */
 }