i965/vs: Add a new dst_reg constructor for file, number, type, and mask.

This will be especially useful for loading texturing parameters, where I
need to (for example) reference m3.xz<D>.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/mesa/drivers/dri/i965/brw_vec4.h

@@ -210,6 +210,16 @@ public:
       this->reg = reg;
    }
 
+   dst_reg(register_file file, int reg, const glsl_type *type, int writemask)
+   {
+      init();
+
+      this->file = file;
+      this->reg = reg;
+      this->type = brw_type_for_base_type(type);
+      this->writemask = writemask;
+   }
+
    dst_reg(struct brw_reg reg)
    {
       init();