suite_aggrs: - added support to gen unions in addition to structs - regenerated struct/union-mixed and nested cases - made rand-sig.lua ignore closing struct/union chars if not opened, effectively reducing number of empty aggregates as it now generated way too much

suite_aggrs for dyncall written in C and Lua.

Tests aggregates (structs, unions) passed by value, along with other,
non-aggregate args.

A macro AGGR_MISALIGN can be used in globals.c to intentionally misalign
aggregate instances.