Add options to skip unavailable locals

Add options to skip unavailable locals

This is the patch to add new option '--skip-unavailable' to MI
commands '-stack-list-{locals, arguments, variables}'.  This patch
extends list_args_or_locals to add a new parameter 'skip_unavailable',
and don't list locals or arguments if values are unavailable and
'skip_unavailable' is true.

This is inspecting a trace frame (tfind mode), where only a few
locals have been collected.

-stack-list-locals, no switch vs new switch:

 -stack-list-locals --simple-values
 ^done,locals=[{name="array",type="unsigned char [2]"},{name="i",type="int",value="<unavailable>"}]
 -stack-list-locals --skip-unavailable --simple-values
 ^done,locals=[{name="array",type="unsigned char [2]"}]

-stack-list-arguments, no switch vs new switch:

 -stack-list-arguments --simple-values
 ^done,stack-args=[frame={level="0",args=[{name="j",type="int",value="4"},{name="s",type="char *",value="<unavailable>"}]},frame={level="1",args=[]}]
 -stack-list-arguments --skip-unavailable --simple-values
 ^done,stack-args=[frame={level="0",args=[{name="j",type="int",value="4"}]},frame={level="1",args=[]}]

-stack-list-variables, no switch vs new switch:

 -stack-list-variables --simple-values
 ^done,variables=[{name="j",arg="1",type="int",value="4"},{name="s",arg="1",type="char *",value="<unavailable>"},{name="array",type="unsigned char [2]"},{name="i",type="int",value="<unavailable>"}]
 -stack-list-variables --skip-unavailable --simple-values
 ^done,variables=[{name="j",arg="1",type="int",value="4"},{name="array",type="unsigned char [2]"}]

tests are added to test these new options.

gdb:

2013-08-27  Pedro Alves  <pedro@codesourcery.com>
	    Yao Qi  <yao@codesourcery.com>

	* mi/mi-cmd-stack.c (list_args_or_locals): Adjust prototype.
	(parse_no_frames_option): Remove.
	(mi_cmd_stack_list_locals): Handle --skip-unavailable.
	(mi_cmd_stack_list_args): Adjust.
	(mi_cmd_stack_list_variables): Handle --skip-unavailable.
	(list_arg_or_local): Add new parameter 'skip_unavailable'.  Return
	early if SKIP_UNAVAILABLE is true and ARG->val is unavailable.
	Caller update.
	(list_args_or_locals): New parameter 'skip_unavailable'.
	Handle it.
	* valprint.c (scalar_type_p): Rename to ...
	(val_print_scalar_type_p): ... this.  Make extern.
	(val_print, value_check_printable): Adjust.
	* valprint.h (val_print_scalar_type_p): Declare.
	* value.c (value_entirely_unavailable): New function.
	* value.h (value_entirely_unavailable): Declare.

	* NEWS: Mention the new option "--skip-unavailable" to MI
	commands '-stack-list-locals', '-stack-list-arguments' and
	'-stack-list-variables'.

gdb/doc:

2013-08-27  Pedro Alves  <pedro@codesourcery.com>
	    Yao Qi  <yao@codesourcery.com>

	* gdb.texinfo (GDB/MI Stack Manipulation) <-stack-list-locals>:
	Document new --skip-unavailable option.
	<-stack-list-variables>: Document new --skip-unavailable option.

gdb/testsuite:

2013-08-27  Yao Qi  <yao@codesourcery.com>

	* gdb.trace/entry-values.exp: Test unavailable entry value is
	not shown when option '--skip-unavailable' is specified.
	* gdb.trace/mi-trace-unavailable.exp (test_trace_unavailable):
	Add tests for new option '--skip-unavailable'.