fix incorrect sampler numbering/indexing.

All samplers indexes were zero.
diff --git a/src/mesa/shader/prog_parameter.h b/src/mesa/shader/prog_parameter.h
index d6cc034..105f6f2 100644
--- a/src/mesa/shader/prog_parameter.h
+++ b/src/mesa/shader/prog_parameter.h
@@ -114,7 +114,7 @@
 
 extern GLint
 _mesa_add_sampler(struct gl_program_parameter_list *paramList,
-                  const char *name, GLenum datatype, GLuint index);
+                  const char *name, GLenum datatype);
 
 extern GLint
 _mesa_add_varying(struct gl_program_parameter_list *paramList,