Introduce xlat verbosity styles

Introduce xlat verbosity styles

* defs.h (printxvals_ex): Rename from printxvals, add style argument.
(enum xlat_style): New enumeration.
(printxvals): New macro, a wrapper for printxvals_ex.
(printxval_searchn_ex): Rename from printxval_searchn, add style
argument.
(printxval_searchn): New macro, a wrapper for printxval_searchn_ex.
(printxval_search_ex): New macro, a wrapper for printxval_searchn_ex.
(sprintxval_ex): Rename from sprintxval, add style argument.
(sprintxval): New macro, a wrapper for sprintxval_ex.
(printflags_ex): Add style argument.
(sprintflags_ex): Rename from sprintflags, add style argument.
(sprintflags): New macro, a wrapper for sprintflags_ex.
(printflags64): Pass XLAT_STYLE_ABBREV as a style in printflags_ex call.
* netlink.c (decode_nlmsg_flags): Pass XLAT_STYLE_ABBREV as a style in
printflags_ex call.
* xlat.c (printxvals_ex): Rename from printxvals, add style argument,
handle it.
(sprintxval_ex): Rename from sprintxval, add style argument, handle it.
(printxval_searchn_ex): Rename from printxval_searchn, add style
argument, handle it.
(sprintflags_ex): Rename from sprintflags, add style argument,
handle it.
(printflags_ex): Add style argument, handle it.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>
References: https://github.com/strace/strace/issues/27