re-add MSAA support

(cherry picked from commit f7d80aa00611917bc8ce637136d982b151b8f44f)

This also involved adding the new MSAA fields to driCreateConfigs().

Also, re-add prog_instructions->Sampler field for i965 driver.  Will
have to revisit that.
diff --git a/src/mesa/shader/prog_instruction.h b/src/mesa/shader/prog_instruction.h
index f978334..c649b3d 100644
--- a/src/mesa/shader/prog_instruction.h
+++ b/src/mesa/shader/prog_instruction.h
@@ -418,7 +418,7 @@
     */
    GLint BranchTarget;
 
-#if 0
+#if 01 /* XXX just use this for i965 driver for now! */
    /**
     * For TEX instructions in shaders, the sampler to use for the
     * texture lookup.