Merge branch 'nd/attr-optim'

Optimize attribute look-up, mostly useful in "git grep" on a project that does not use many attributes, by avoiding it when we (should) know that the attributes are not defined in the first place. * nd/attr-optim: attr: avoid heavy work when we know the specified attr is not defined attr: do not attempt to expand when we know it's not a macro attr.c: rename arg name attr_nr to avoid shadowing the global one