ABI TODO

Remaining ABI items to address -:

Document ABI/API calling conventions for different AROS flavours.

Document soft-float being the default API calling convention.

implement handling of softfloat env -:

int feclearexcept(int __excepts)
int fegetexceptflag(fexcept_t *__flagp, int __excepts)
int fesetexceptflag(const fexcept_t *__flagp, int __excepts)
int feraiseexcept(int __excepts)
int fetestexcept(int __excepts)
int fegetround(void)
int fesetround(int __round)
int fegetenv(fenv_t *__envp)
int feholdexcept(fenv_t *__envp)
int fesetenv(const fenv_t *__envp)
int feupdateenv(const fenv_t *__envp)