* valprint.c (val_print): Extend comment.
* ada-valprint.c (ada_valprint): Rewrite comment deferring
interface explanation to val_print.
(ada_val_print_array): Adjust comment to current interface.
(print_field_values): Adjust comment to current interface.
* c-valprint.c (c_val_print): Rewrite comment deferring interface
explanation to val_print.
* f-valprint.c (f_val_print): Ditto.
* jv-valprint.c (java_val_print): Ditto.
* m2-valprint.c (m2_val_print): Ditto.
* p-valprint.c (pascal_val_print): Ditto.