chroma: tidy plugin simd variant flags
...to use short labels like PLAIN_PLUGIN
and SSE2_PLUGIN
rather than
MODULE_NAME_IS_xxx_yyy[_zzz]
. this makes the code cleaner, easier to read,
and improves consistency. it also helps remove a source of plugin vs.
module confusion.
trying to recognise that something like MODULE_NAME_IS_i420_yuy2
refers
to the 'plain' variant, compared to MODULE_NAME_IS_i420_yuy2_sse2
for the
SSE2 variant, was problematic.
the i420_rgb plugin used short MMX
type defines. these have been changed
to MMX_PLUGIN
style for consistency.
--
also, added extra commit, in relation to discussion below, addressing similar flags in two other plugins.
Edited by Lyndon Brown