Rewrite S21 so that Zavolaj/NativeCall is spec foreign function interface.
Rewrite S21 so that Zavolaj/NativeCall is spec foreign function interface.

This is a complete rewrite of this synopsis. The document that was here was
extremely short, and didn't really spec anything. There some mention of
importing Perl 5 code, however. If this is missed, it should probably be
incorporated into S11.

tokuhirom/specs,tokuhirom/specs,perl6/specs,prammer/specs,perl6/specs,prammer/specs,prammer/specs,tokuhirom/specs