test/utils: support format name aliases

test/utils: support format name aliases

Previously there was a flat list of formats, used to iterate over all
formats when looking up a format from name or listing them. This cannot
support name aliases.

To support name aliases (multiple name strings mapping to the same
format), create a format-name mapping table. Functions format_name(),
format_from_string(), and list_formats() should keep on working exactly
like before, except format_from_string() now recognizes the additional
formats that format_name() already supported.

The only the formats from the old format list are added with ENTRY, so
that list_formats() works as before. The whole list is verified against
the authoritative list in pixman.h, entries missing from the old list
are commented out.

The extra formats supported by the old format_name() are added as
ALIASes. A side-effect of that is that now also format_from_string()
recognizes the following new names: x4c4 / c8, x4g4 / g8, c4, g4, g1,
yuy2, yv12, null, solid, pixbuf, rpixbuf, unknown.

Name aliases will be useful in follow-up patches, where
lowlevel-blt-bench.c is converted to parse short-hand format names from
strings.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ben Avison <bavison@riscosopen.org>