Print capability pointers as capabilities

Print capability pointers as capabilities

Print capability pointers as capabilities, so the user can see the
decoded fields of the capability.

gdb/ChangeLog:

2020-11-11  Luis Machado  <luis.machado@arm.com>

	* c-valprint.c (c_value_print_ptr): Adjust to print capability
	pointers as capabilities.
	(c_value_print_inner): Handle TYPE_CODE_CAPABILITY.
	* findvar.c (extract_integer): Truncate scalars instead of erroring out.
	* valprint.c (generic_value_print_capability): Make non-static and
	print additional space.
	* valprint.h (generic_value_print_capability): New prototype.