This is an attempt at splitting cold code from regular code in a function. All landing pads are considered cold (in fact, they almost always are, especially if performance is a concern, and assuming this allow for simplification in the LSDA).
2 LSDA header and call sites are emited, the cold one nested within the regular one. They both share the same action table and type table.
A symbol is amited for the cold function, using the name of the function suffixed by $cold . Emiting a symbol is required when using .subsections_via_symbols .
Debug informations aren't supported at this stage.