mesa: don't update draw buffer bounds in _mesa_update_state

st/mesa doesn't need the draw bounds for draw calls. I've added the call
where it's necessary in core Mesa and drivers, but I suspect that most
drivers can just move the call to the right places.

The core Mesa places aren't hot paths, so the call overhead doesn't matter
there.

For now, only st/mesa is made such that this function is invoked very
rarely.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/mesa/state_tracker/st_cb_clear.c

@@ -36,6 +36,7 @@
 #include "main/glheader.h"
 #include "main/accum.h"
 #include "main/formats.h"
+#include "main/framebuffer.h"
 #include "main/macros.h"
 #include "main/glformats.h"
 #include "program/prog_instruction.h"
@@ -179,6 +180,9 @@ clear_with_quad(struct gl_context *ctx, unsigned clear_buffers)
    const struct gl_framebuffer *fb = ctx->DrawBuffer;
    const GLfloat fb_width = (GLfloat) fb->Width;
    const GLfloat fb_height = (GLfloat) fb->Height;
+
+   _mesa_update_draw_buffer_bounds(ctx, ctx->DrawBuffer);
+
    const GLfloat x0 = (GLfloat) ctx->DrawBuffer->_Xmin / fb_width * 2.0f - 1.0f;
    const GLfloat x1 = (GLfloat) ctx->DrawBuffer->_Xmax / fb_width * 2.0f - 1.0f;
    const GLfloat y0 = (GLfloat) ctx->DrawBuffer->_Ymin / fb_height * 2.0f - 1.0f;