DIP56 Provide pragma to control function inlining

[Araq]

>
> The fact that original C "inline" was designed in same 
> "permissive" way and is almost unused in practice (as opposed 
> to compiler-specific force_inline attributes) does say 
> something.
>

Do you mind to back up your "fact" with some numbers? Afaict 
'inline' is more common than __attribute__((forceinline)). (Well 
ok for C code #define is even more common, but most C code is 
stuck in the 70ies anyway so that doesn't mean anything.)