Import a security patch from the mainline which changes the default behaviour

Import a security patch from the mainline which changes the default behaviour
of the strings program to be --all rather then --data.  This avoids using the
BFD library by default, and so avoids exposing strings to any memory bugs
present in BFD.

	* strings.c: Add new command line option --data to only scan the
	initialized, loadable data secions of binaries.  Choose the
	default behaviour of --all or --data based upon a configure
	option.
	* doc/binutils.texi (strings): Update documentation.  Include
	description  of why the --data option might be unsafe.
	* configure.ac: Add new option --disable-default-strings-all which
	restores the old behaviour of strings using --data by default.  If
	the option is not used make strings use --all by default.
	* NEWS: Mention the new behaviour of strings.
	* configure: Regenerate.
	* config.in: Regenerate.