get_int_var_value

get_int_var_value

I noticed that get_int_var_value's parameters could use some
constification.  And then realized that client code would become
simpler by changing the interface to return the success/failure
indication as actual return value, as it allows getting rid of the
local "boolean" variable.

gdb/ChangeLog:
2017-07-20  Pedro Alves  <palves@redhat.com>

	* ada-lang.c (ada_to_fixed_type_1): Adjust.
	(get_var_value): Constify parameters.
	(get_int_var_value): Change prototype.
	(to_fixed_range_type): Adjust.
	* ada-lang.h (get_int_var_value): Change prototype.