:language defaults to :C (flag 512) for functions defined via
1. document the default ("Choice of C flavour") in impnotes.html
2. change the default to :stdc (ANSI) instead of :C (K&R)
Cost of change, to users: def-c-call-in/out is unaffected, and I =
believe only a tiny portion of users ever used c-function directly. =
Most stuff just passes ints and c-strings around.
In todays's context, I find it not meeting common sense expectations =
about program behaviour that things defined via (ffi:c-function =
(:arguments ...)) must not forget (:language :stdc) or they'll get K&R =
:C calling conventions.
3. please document what :stdc-stdcall means.