This patch removes the parameter valaddr of
extension_language_ops::apply_val_pretty_printer and remove const from
"struct value *val".  valaddr can be got in each extension language's
implementation of apply_val_pretty_printer.

gdb:

2016-11-11  Yao Qi  <yao.qi@linaro.org>

	* cp-valprint.c (cp_print_value): Remove local base_valaddr.
	* extension-priv.h (struct extension_language_ops)
	<apply_val_pretty_printer>: Remove the second parameter.
	Remove const from "struct value *".  Callers updated.
	* extension.c (apply_ext_lang_val_pretty_printer): Update
	comments.  Remove parameter valaddr.  Remove const from
	"struct value *".
	* extension.h (apply_ext_lang_val_pretty_printer): Update
	declaration.
	* guile/guile-internal.h (gdbscm_apply_val_pretty_printer):
	Update declaration.
	* guile/scm-pretty-print.c (gdbscm_apply_val_pretty_printer):
	Remove parameter valaddr.  Remove const from "struct value *".
	* python/py-prettyprint.c (gdbpy_apply_val_pretty_printer):
	Likewise.
	* python/python-internal.h (gdbpy_apply_val_pretty_printer):
	Update declaration.