shaders: Don't lose the param binding swizzle for single params.

Multiple item params are OK because we don't allow swizzles for them
(in case you do array access to hit their elements, for example).  For
singles, though, using the swizzle can cut down on storage, we do want
to allow a swizzled use of another param.

Fixes OGLC texRect.c.

src/mesa/shader/program_parse.tab.c

@@ -3366,7 +3366,7 @@ yyreduce:
 	      s->param_binding_type = (yyvsp[(3) - (3)].temp_sym).param_binding_type;
 	      s->param_binding_begin = (yyvsp[(3) - (3)].temp_sym).param_binding_begin;
 	      s->param_binding_length = (yyvsp[(3) - (3)].temp_sym).param_binding_length;
-              s->param_binding_swizzle = SWIZZLE_XYZW;
+              s->param_binding_swizzle = (yyvsp[(3) - (3)].temp_sym).param_binding_swizzle;
 	      s->param_is_array = 0;
 	   }
 	;}

src/mesa/shader/program_parse.y

@@ -1219,7 +1219,7 @@ PARAM_singleStmt: PARAM IDENTIFIER paramSingleInit
 	      s->param_binding_type = $3.param_binding_type;
 	      s->param_binding_begin = $3.param_binding_begin;
 	      s->param_binding_length = $3.param_binding_length;
-              s->param_binding_swizzle = SWIZZLE_XYZW;
+              s->param_binding_swizzle = $3.param_binding_swizzle;
 	      s->param_is_array = 0;
 	   }
 	}